keys = returnedItem.keySet();
System.out.println("Amazon DynamoDB table attributes: \n");
for (String key1 : keys) {
System.out.format("%s: %s\n", key1, returnedItem.get(key1).toString());
}
} else {
System.out.format("No item found with the key %s!\n", "year");
}
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
}
```
Full example.
```
/**
* Before running this Java V2 code example, set up your development
* environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*
* This Java example performs these tasks:
*
* 1. Creates the Amazon DynamoDB Movie table with partition and sort key.
* 2. Puts data into the Amazon DynamoDB table from a JSON document using the
* Enhanced client.
* 3. Gets data from the Movie table.
* 4. Adds a new item.
* 5. Updates an item.
* 6. Uses a Scan to query items using the Enhanced client.
* 7. Queries all items where the year is 2013 using the Enhanced Client.
* 8. Deletes the table.
*/
public class Scenario {
public static final String DASHES = new String(new char[80]).replace("\0", "-");
public static void main(String[] args) throws IOException {
String tableName = "Movies";
String fileName = "../../../resources/sample_files/movies.json";
Region region = Region.US_EAST_1;
DynamoDbClient ddb = DynamoDbClient.builder()
.region(region)
.build();
System.out.println(DASHES);
System.out.println("Welcome to the Amazon DynamoDB example scenario.");
System.out.println(DASHES);
System.out.println(DASHES);
System.out.println(
"1. Creating an Amazon DynamoDB table named Movies with a key named year and a sort key named title.");
createTable(ddb, tableName);
System.out.println(DASHES);
System.out.println(DASHES);
System.out.println("2. Loading data into the Amazon DynamoDB table.");
loadData(ddb, tableName, fileName);
System.out.println(DASHES);
System.out.println(DASHES);
System.out.println("3. Getting data from the Movie table.");
getItem(ddb);
System.out.println(DASHES);
System.out.println(DASHES);
System.out.println("4. Putting a record into the Amazon DynamoDB table.");
putRecord(ddb);
System.out.println(DASHES);
System.out.println(DASHES);
System.out.println("5. Updating a record.");
updateTableItem(ddb, tableName);
System.out.println(DASHES);
System.out.println(DASHES);
System.out.println("6. Scanning the Amazon DynamoDB table.");
scanMovies(ddb, tableName);
System.out.println(DASHES);
System.out.println(DASHES);
System.out.println("7. Querying the Movies released in 2013.");
queryTable(ddb);
System.out.println(DASHES);
System.out.println(DASHES);
System.out.println("8. Deleting the Amazon DynamoDB table.");
deleteDynamoDBTable(ddb, tableName);
System.out.println(DASHES);
ddb.close();
}
// Create a table with a Sort key.
public static void createTable(DynamoDbClient ddb, String tableName) {
DynamoDbWaiter dbWaiter = ddb.waiter();
ArrayList attributeDefinitions = new ArrayList<>();
// Define attributes.
attributeDefinitions.add(AttributeDefinition.builder()
.attributeName("year")
.attributeType("N")
.build());
attributeDefinitions.add(AttributeDefinition.builder()
.attributeName("title")
.attributeType("S")
.build());
ArrayList tableKey = new ArrayList<>();
KeySchemaElement key = KeySchemaElement.builder()
.attributeName("year")
.keyType(KeyType.HASH)
.build();
KeySchemaElement key2 = KeySchemaElement.builder()
.attributeName("title")
.keyType(KeyType.RANGE)
.build();
// Add KeySchemaElement objects to the list.
tableKey.add(key);
tableKey.add(key2);
CreateTableRequest request = CreateTableRequest.builder()
.keySchema(tableKey)
.billingMode(BillingMode.PAY_PER_REQUEST) // DynamoDB automatically scales based on traffic.
.attributeDefinitions(attributeDefinitions)
.tableName(tableName)
.build();
try {
CreateTableResponse response = ddb.createTable(request);
DescribeTableRequest tableRequest = DescribeTableRequest.builder()
.tableName(tableName)
.build();
// Wait until the Amazon DynamoDB table is created.
WaiterResponse waiterResponse = dbWaiter.waitUntilTableExists(tableRequest);
waiterResponse.matched().response().ifPresent(System.out::println);
String newTable = response.tableDescription().tableName();
System.out.println("The " + newTable + " was successfully created.");
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
}
// Query the table.
public static void queryTable(DynamoDbClient ddb) {
try {
DynamoDbEnhancedClient enhancedClient = DynamoDbEnhancedClient.builder()
.dynamoDbClient(ddb)
.build();
DynamoDbTable custTable = enhancedClient.table("Movies", TableSchema.fromBean(Movies.class));
QueryConditional queryConditional = QueryConditional
.keyEqualTo(Key.builder()
.partitionValue(2013)
.build());
// Get items in the table and write out the ID value.
Iterator results = custTable.query(queryConditional).items().iterator();
String result = "";
while (results.hasNext()) {
Movies rec = results.next();
System.out.println("The title of the movie is " + rec.getTitle());
System.out.println("The movie information is " + rec.getInfo());
}
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
}
// Scan the table.
public static void scanMovies(DynamoDbClient ddb, String tableName) {
System.out.println("******* Scanning all movies.\n");
try {
DynamoDbEnhancedClient enhancedClient = DynamoDbEnhancedClient.builder()
.dynamoDbClient(ddb)
.build();
DynamoDbTable custTable = enhancedClient.table("Movies", TableSchema.fromBean(Movies.class));
Iterator results = custTable.scan().items().iterator();
while (results.hasNext()) {
Movies rec = results.next();
System.out.println("The movie title is " + rec.getTitle());
System.out.println("The movie year is " + rec.getYear());
}
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
}
// Load data into the table.
public static void loadData(DynamoDbClient ddb, String tableName, String fileName) throws IOException {
DynamoDbEnhancedClient enhancedClient = DynamoDbEnhancedClient.builder()
.dynamoDbClient(ddb)
.build();
DynamoDbTable mappedTable = enhancedClient.table("Movies", TableSchema.fromBean(Movies.class));
JsonParser parser = new JsonFactory().createParser(new File(fileName));
com.fasterxml.jackson.databind.JsonNode rootNode = new ObjectMapper().readTree(parser);
Iterator iter = rootNode.iterator();
ObjectNode currentNode;
int t = 0;
while (iter.hasNext()) {
// Only add 200 Movies to the table.
if (t == 200)
break;
currentNode = (ObjectNode) iter.next();
int year = currentNode.path("year").asInt();
String title = currentNode.path("title").asText();
String info = currentNode.path("info").toString();
Movies movies = new Movies();
movies.setYear(year);
movies.setTitle(title);
movies.setInfo(info);
// Put the data into the Amazon DynamoDB Movie table.
mappedTable.putItem(movies);
t++;
}
}
// Update the record to include show only directors.
public static void updateTableItem(DynamoDbClient ddb, String tableName) {
HashMap itemKey = new HashMap<>();
itemKey.put("year", AttributeValue.builder().n("1933").build());
itemKey.put("title", AttributeValue.builder().s("King Kong").build());
HashMap updatedValues = new HashMap<>();
updatedValues.put("info", AttributeValueUpdate.builder()
.value(AttributeValue.builder().s("{\"directors\":[\"Merian C. Cooper\",\"Ernest B. Schoedsack\"]")
.build())
.action(AttributeAction.PUT)
.build());
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(itemKey)
.attributeUpdates(updatedValues)
.build();
try {
ddb.updateItem(request);
} catch (ResourceNotFoundException e) {
System.err.println(e.getMessage());
System.exit(1);
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
System.out.println("Item was updated!");
}
public static void deleteDynamoDBTable(DynamoDbClient ddb, String tableName) {
DeleteTableRequest request = DeleteTableRequest.builder()
.tableName(tableName)
.build();
try {
ddb.deleteTable(request);
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
System.out.println(tableName + " was successfully deleted!");
}
public static void putRecord(DynamoDbClient ddb) {
try {
DynamoDbEnhancedClient enhancedClient = DynamoDbEnhancedClient.builder()
.dynamoDbClient(ddb)
.build();
DynamoDbTable table = enhancedClient.table("Movies", TableSchema.fromBean(Movies.class));
// Populate the Table.
Movies record = new Movies();
record.setYear(2020);
record.setTitle("My Movie2");
record.setInfo("no info");
table.putItem(record);
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
System.out.println("Added a new movie to the table.");
}
public static void getItem(DynamoDbClient ddb) {
HashMap keyToGet = new HashMap<>();
keyToGet.put("year", AttributeValue.builder()
.n("1933")
.build());
keyToGet.put("title", AttributeValue.builder()
.s("King Kong")
.build());
GetItemRequest request = GetItemRequest.builder()
.key(keyToGet)
.tableName("Movies")
.build();
try {
Map returnedItem = ddb.getItem(request).item();
if (returnedItem != null) {
Set keys = returnedItem.keySet();
System.out.println("Amazon DynamoDB table attributes: \n");
for (String key1 : keys) {
System.out.format("%s: %s\n", key1, returnedItem.get(key1).toString());
}
} else {
System.out.format("No item found with the key %s!\n", "year");
}
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
}
}
```
+ For API details, see the following topics in *AWS SDK for Java 2.x API Reference*.
+ [BatchWriteItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/BatchWriteItem)
+ [CreateTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/CreateTable)
+ [DeleteItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/DeleteItem)
+ [DeleteTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/DeleteTable)
+ [DescribeTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/DescribeTable)
+ [GetItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/GetItem)
+ [PutItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/PutItem)
+ [Query](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/Query)
+ [Scan](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/Scan)
+ [UpdateItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/UpdateItem)
## Actions
### `BatchGetItem`
The following code example shows how to use `BatchGetItem`.
**SDK for Java 2.x**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/dynamodb#code-examples).
Shows how to get batch items using the service client.
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.BatchGetItemRequest;
import software.amazon.awssdk.services.dynamodb.model.BatchGetItemResponse;
import software.amazon.awssdk.services.dynamodb.model.KeysAndAttributes;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Before running this Java V2 code example, set up your development environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*/
public class BatchReadItems {
public static void main(String[] args){
final String usage = """
Usage:
Where:
tableName - The Amazon DynamoDB table (for example, Music).\s
""";
String tableName = "Music";
Region region = Region.US_EAST_1;
DynamoDbClient dynamoDbClient = DynamoDbClient.builder()
.region(region)
.build();
getBatchItems(dynamoDbClient, tableName);
}
public static void getBatchItems(DynamoDbClient dynamoDbClient, String tableName) {
// Define the primary key values for the items you want to retrieve.
Map key1 = new HashMap<>();
key1.put("Artist", AttributeValue.builder().s("Artist1").build());
Map key2 = new HashMap<>();
key2.put("Artist", AttributeValue.builder().s("Artist2").build());
// Construct the batchGetItem request.
Map requestItems = new HashMap<>();
requestItems.put(tableName, KeysAndAttributes.builder()
.keys(List.of(key1, key2))
.projectionExpression("Artist, SongTitle")
.build());
BatchGetItemRequest batchGetItemRequest = BatchGetItemRequest.builder()
.requestItems(requestItems)
.build();
// Make the batchGetItem request.
BatchGetItemResponse batchGetItemResponse = dynamoDbClient.batchGetItem(batchGetItemRequest);
// Extract and print the retrieved items.
Map>> responses = batchGetItemResponse.responses();
if (responses.containsKey(tableName)) {
List> musicItems = responses.get(tableName);
for (Map item : musicItems) {
System.out.println("Artist: " + item.get("Artist").s() +
", SongTitle: " + item.get("SongTitle").s());
}
} else {
System.out.println("No items retrieved.");
}
}
}
```
Shows how to get batch items using the service client and a paginator.
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.BatchGetItemRequest;
import software.amazon.awssdk.services.dynamodb.model.KeysAndAttributes;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class BatchGetItemsPaginator {
public static void main(String[] args){
final String usage = """
Usage:
Where:
tableName - The Amazon DynamoDB table (for example, Music).\s
""";
String tableName = "Music";
Region region = Region.US_EAST_1;
DynamoDbClient dynamoDbClient = DynamoDbClient.builder()
.region(region)
.build();
getBatchItemsPaginator(dynamoDbClient, tableName) ;
}
public static void getBatchItemsPaginator(DynamoDbClient dynamoDbClient, String tableName) {
// Define the primary key values for the items you want to retrieve.
Map key1 = new HashMap<>();
key1.put("Artist", AttributeValue.builder().s("Artist1").build());
Map key2 = new HashMap<>();
key2.put("Artist", AttributeValue.builder().s("Artist2").build());
// Construct the batchGetItem request.
Map requestItems = new HashMap<>();
requestItems.put(tableName, KeysAndAttributes.builder()
.keys(List.of(key1, key2))
.projectionExpression("Artist, SongTitle")
.build());
BatchGetItemRequest batchGetItemRequest = BatchGetItemRequest.builder()
.requestItems(requestItems)
.build();
// Use batchGetItemPaginator for paginated requests.
dynamoDbClient.batchGetItemPaginator(batchGetItemRequest).stream()
.flatMap(response -> response.responses().getOrDefault(tableName, Collections.emptyList()).stream())
.forEach(item -> {
System.out.println("Artist: " + item.get("Artist").s() +
", SongTitle: " + item.get("SongTitle").s());
});
}
}
```
+ For API details, see [BatchGetItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/BatchGetItem) in *AWS SDK for Java 2.x API Reference*.
### `BatchWriteItem`
The following code example shows how to use `BatchWriteItem`.
**SDK for Java 2.x**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/dynamodb/#code-examples).
Inserts many items into a table by using the service client.
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.BatchWriteItemRequest;
import software.amazon.awssdk.services.dynamodb.model.BatchWriteItemResponse;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.PutRequest;
import software.amazon.awssdk.services.dynamodb.model.WriteRequest;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Before running this Java V2 code example, set up your development environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*/
public class BatchWriteItems {
public static void main(String[] args){
final String usage = """
Usage:
Where:
tableName - The Amazon DynamoDB table (for example, Music).\s
""";
String tableName = "Music";
Region region = Region.US_EAST_1;
DynamoDbClient dynamoDbClient = DynamoDbClient.builder()
.region(region)
.build();
addBatchItems(dynamoDbClient, tableName);
}
public static void addBatchItems(DynamoDbClient dynamoDbClient, String tableName) {
// Specify the updates you want to perform.
List writeRequests = new ArrayList<>();
// Set item 1.
Map item1Attributes = new HashMap<>();
item1Attributes.put("Artist", AttributeValue.builder().s("Artist1").build());
item1Attributes.put("Rating", AttributeValue.builder().s("5").build());
item1Attributes.put("Comments", AttributeValue.builder().s("Great song!").build());
item1Attributes.put("SongTitle", AttributeValue.builder().s("SongTitle1").build());
writeRequests.add(WriteRequest.builder().putRequest(PutRequest.builder().item(item1Attributes).build()).build());
// Set item 2.
Map item2Attributes = new HashMap<>();
item2Attributes.put("Artist", AttributeValue.builder().s("Artist2").build());
item2Attributes.put("Rating", AttributeValue.builder().s("4").build());
item2Attributes.put("Comments", AttributeValue.builder().s("Nice melody.").build());
item2Attributes.put("SongTitle", AttributeValue.builder().s("SongTitle2").build());
writeRequests.add(WriteRequest.builder().putRequest(PutRequest.builder().item(item2Attributes).build()).build());
try {
// Create the BatchWriteItemRequest.
BatchWriteItemRequest batchWriteItemRequest = BatchWriteItemRequest.builder()
.requestItems(Map.of(tableName, writeRequests))
.build();
// Execute the BatchWriteItem operation.
BatchWriteItemResponse batchWriteItemResponse = dynamoDbClient.batchWriteItem(batchWriteItemRequest);
// Process the response.
System.out.println("Batch write successful: " + batchWriteItemResponse);
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
}
}
```
Inserts many items into a table by using the enhanced client.
```
import com.example.dynamodb.Customer;
import com.example.dynamodb.Music;
import software.amazon.awssdk.enhanced.dynamodb.DynamoDbEnhancedClient;
import software.amazon.awssdk.enhanced.dynamodb.DynamoDbTable;
import software.amazon.awssdk.enhanced.dynamodb.Key;
import software.amazon.awssdk.enhanced.dynamodb.TableSchema;
import software.amazon.awssdk.enhanced.dynamodb.model.BatchWriteItemEnhancedRequest;
import software.amazon.awssdk.enhanced.dynamodb.model.WriteBatch;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.ZoneOffset;
/*
* Before running this code example, create an Amazon DynamoDB table named Customer with these columns:
* - id - the id of the record that is the key
* - custName - the customer name
* - email - the email value
* - registrationDate - an instant value when the item was added to the table
*
* Also, ensure that you have set up your development environment, including your credentials.
*
* For information, see this documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*/
public class EnhancedBatchWriteItems {
public static void main(String[] args) {
Region region = Region.US_EAST_1;
DynamoDbClient ddb = DynamoDbClient.builder()
.region(region)
.build();
DynamoDbEnhancedClient enhancedClient = DynamoDbEnhancedClient.builder()
.dynamoDbClient(ddb)
.build();
putBatchRecords(enhancedClient);
ddb.close();
}
public static void putBatchRecords(DynamoDbEnhancedClient enhancedClient) {
try {
DynamoDbTable customerMappedTable = enhancedClient.table("Customer",
TableSchema.fromBean(Customer.class));
DynamoDbTable musicMappedTable = enhancedClient.table("Music",
TableSchema.fromBean(Music.class));
LocalDate localDate = LocalDate.parse("2020-04-07");
LocalDateTime localDateTime = localDate.atStartOfDay();
Instant instant = localDateTime.toInstant(ZoneOffset.UTC);
Customer record2 = new Customer();
record2.setCustName("Fred Pink");
record2.setId("id110");
record2.setEmail("fredp@noserver.com");
record2.setRegistrationDate(instant);
Customer record3 = new Customer();
record3.setCustName("Susan Pink");
record3.setId("id120");
record3.setEmail("spink@noserver.com");
record3.setRegistrationDate(instant);
Customer record4 = new Customer();
record4.setCustName("Jerry orange");
record4.setId("id101");
record4.setEmail("jorange@noserver.com");
record4.setRegistrationDate(instant);
BatchWriteItemEnhancedRequest batchWriteItemEnhancedRequest = BatchWriteItemEnhancedRequest
.builder()
.writeBatches(
WriteBatch.builder(Customer.class) // add items to the Customer
// table
.mappedTableResource(customerMappedTable)
.addPutItem(builder -> builder.item(record2))
.addPutItem(builder -> builder.item(record3))
.addPutItem(builder -> builder.item(record4))
.build(),
WriteBatch.builder(Music.class) // delete an item from the Music
// table
.mappedTableResource(musicMappedTable)
.addDeleteItem(builder -> builder.key(
Key.builder().partitionValue(
"Famous Band")
.build()))
.build())
.build();
// Add three items to the Customer table and delete one item from the Music
// table.
enhancedClient.batchWriteItem(batchWriteItemEnhancedRequest);
System.out.println("done");
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
}
}
```
+ For API details, see [BatchWriteItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/BatchWriteItem) in *AWS SDK for Java 2.x API Reference*.
### `CreateTable`
The following code example shows how to use `CreateTable`.
**SDK for Java 2.x**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/dynamodb#code-examples).
```
import software.amazon.awssdk.core.waiters.WaiterResponse;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeDefinition;
import software.amazon.awssdk.services.dynamodb.model.BillingMode;
import software.amazon.awssdk.services.dynamodb.model.CreateTableRequest;
import software.amazon.awssdk.services.dynamodb.model.CreateTableResponse;
import software.amazon.awssdk.services.dynamodb.model.DescribeTableRequest;
import software.amazon.awssdk.services.dynamodb.model.DescribeTableResponse;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.KeySchemaElement;
import software.amazon.awssdk.services.dynamodb.model.KeyType;
import software.amazon.awssdk.services.dynamodb.model.OnDemandThroughput;
import software.amazon.awssdk.services.dynamodb.model.ProvisionedThroughput;
import software.amazon.awssdk.services.dynamodb.model.ScalarAttributeType;
import software.amazon.awssdk.services.dynamodb.waiters.DynamoDbWaiter;
/**
* Before running this Java V2 code example, set up your development
* environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*/
public class CreateTable {
public static void main(String[] args) {
final String usage = """
Usage:
Where:
tableName - The Amazon DynamoDB table to create (for example, Music3).
key - The key for the Amazon DynamoDB table (for example, Artist).
""";
if (args.length != 2) {
System.out.println(usage);
System.exit(1);
}
String tableName = args[0];
String key = args[1];
System.out.println("Creating an Amazon DynamoDB table " + tableName + " with a simple primary key: " + key);
Region region = Region.US_EAST_1;
DynamoDbClient ddb = DynamoDbClient.builder()
.region(region)
.build();
String result = createTable(ddb, tableName, key);
System.out.println("New table is " + result);
ddb.close();
}
public static String createTable(DynamoDbClient ddb, String tableName, String key) {
DynamoDbWaiter dbWaiter = ddb.waiter();
CreateTableRequest request = CreateTableRequest.builder()
.attributeDefinitions(AttributeDefinition.builder()
.attributeName(key)
.attributeType(ScalarAttributeType.S)
.build())
.keySchema(KeySchemaElement.builder()
.attributeName(key)
.keyType(KeyType.HASH)
.build())
.billingMode(BillingMode.PAY_PER_REQUEST) // DynamoDB automatically scales based on traffic.
.tableName(tableName)
.build();
String newTable;
try {
CreateTableResponse response = ddb.createTable(request);
DescribeTableRequest tableRequest = DescribeTableRequest.builder()
.tableName(tableName)
.build();
// Wait until the Amazon DynamoDB table is created.
WaiterResponse waiterResponse = dbWaiter.waitUntilTableExists(tableRequest);
waiterResponse.matched().response().ifPresent(System.out::println);
newTable = response.tableDescription().tableName();
return newTable;
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
return "";
}
}
```
+ For API details, see [CreateTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/CreateTable) in *AWS SDK for Java 2.x API Reference*.
### `DeleteItem`
The following code example shows how to use `DeleteItem`.
**SDK for Java 2.x**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/dynamodb#code-examples).
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DeleteItemRequest;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import java.util.HashMap;
/**
* Before running this Java V2 code example, set up your development
* environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*/
public class DeleteItem {
public static void main(String[] args) {
final String usage = """
Usage:
Where:
tableName - The Amazon DynamoDB table to delete the item from (for example, Music3).
key - The key used in the Amazon DynamoDB table (for example, Artist).\s
keyval - The key value that represents the item to delete (for example, Famous Band).
""";
if (args.length != 3) {
System.out.println(usage);
System.exit(1);
}
String tableName = args[0];
String key = args[1];
String keyVal = args[2];
System.out.format("Deleting item \"%s\" from %s\n", keyVal, tableName);
Region region = Region.US_EAST_1;
DynamoDbClient ddb = DynamoDbClient.builder()
.region(region)
.build();
deleteDynamoDBItem(ddb, tableName, key, keyVal);
ddb.close();
}
public static void deleteDynamoDBItem(DynamoDbClient ddb, String tableName, String key, String keyVal) {
HashMap keyToGet = new HashMap<>();
keyToGet.put(key, AttributeValue.builder()
.s(keyVal)
.build());
DeleteItemRequest deleteReq = DeleteItemRequest.builder()
.tableName(tableName)
.key(keyToGet)
.build();
try {
ddb.deleteItem(deleteReq);
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
}
}
```
+ For API details, see [DeleteItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/DeleteItem) in *AWS SDK for Java 2.x API Reference*.
### `DeleteTable`
The following code example shows how to use `DeleteTable`.
**SDK for Java 2.x**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/dynamodb#code-examples).
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.DeleteTableRequest;
/**
* Before running this Java V2 code example, set up your development
* environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*/
public class DeleteTable {
public static void main(String[] args) {
final String usage = """
Usage:
Where:
tableName - The Amazon DynamoDB table to delete (for example, Music3).
**Warning** This program will delete the table that you specify!
""";
if (args.length != 1) {
System.out.println(usage);
System.exit(1);
}
String tableName = args[0];
System.out.format("Deleting the Amazon DynamoDB table %s...\n", tableName);
Region region = Region.US_EAST_1;
DynamoDbClient ddb = DynamoDbClient.builder()
.region(region)
.build();
deleteDynamoDBTable(ddb, tableName);
ddb.close();
}
public static void deleteDynamoDBTable(DynamoDbClient ddb, String tableName) {
DeleteTableRequest request = DeleteTableRequest.builder()
.tableName(tableName)
.build();
try {
ddb.deleteTable(request);
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
System.out.println(tableName + " was successfully deleted!");
}
}
```
+ For API details, see [DeleteTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/DeleteTable) in *AWS SDK for Java 2.x API Reference*.
### `DescribeTable`
The following code example shows how to use `DescribeTable`.
**SDK for Java 2.x**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/dynamodb#code-examples).
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeDefinition;
import software.amazon.awssdk.services.dynamodb.model.DescribeTableRequest;
import software.amazon.awssdk.services.dynamodb.model.ProvisionedThroughputDescription;
import software.amazon.awssdk.services.dynamodb.model.TableDescription;
import java.util.List;
/**
* Before running this Java V2 code example, set up your development
* environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*/
public class DescribeTable {
public static void main(String[] args) {
final String usage = """
Usage:
Where:
tableName - The Amazon DynamoDB table to get information about (for example, Music3).
""";
if (args.length != 1) {
System.out.println(usage);
System.exit(1);
}
String tableName = args[0];
System.out.format("Getting description for %s\n\n", tableName);
Region region = Region.US_EAST_1;
DynamoDbClient ddb = DynamoDbClient.builder()
.region(region)
.build();
describeDymamoDBTable(ddb, tableName);
ddb.close();
}
public static void describeDymamoDBTable(DynamoDbClient ddb, String tableName) {
DescribeTableRequest request = DescribeTableRequest.builder()
.tableName(tableName)
.build();
try {
TableDescription tableInfo = ddb.describeTable(request).table();
if (tableInfo != null) {
System.out.format("Table name : %s\n", tableInfo.tableName());
System.out.format("Table ARN : %s\n", tableInfo.tableArn());
System.out.format("Status : %s\n", tableInfo.tableStatus());
System.out.format("Item count : %d\n", tableInfo.itemCount());
System.out.format("Size (bytes): %d\n", tableInfo.tableSizeBytes());
ProvisionedThroughputDescription throughputInfo = tableInfo.provisionedThroughput();
System.out.println("Throughput");
System.out.format(" Read Capacity : %d\n", throughputInfo.readCapacityUnits());
System.out.format(" Write Capacity: %d\n", throughputInfo.writeCapacityUnits());
List attributes = tableInfo.attributeDefinitions();
System.out.println("Attributes");
for (AttributeDefinition a : attributes) {
System.out.format(" %s (%s)\n", a.attributeName(), a.attributeType());
}
}
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
System.out.println("\nDone!");
}
}
```
+ For API details, see [DescribeTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/DescribeTable) in *AWS SDK for Java 2.x API Reference*.
### `DescribeTimeToLive`
The following code example shows how to use `DescribeTimeToLive`.
**SDK for Java 2.x**
Describe TTL configuration on an existing DynamoDB table using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.DescribeTimeToLiveRequest;
import software.amazon.awssdk.services.dynamodb.model.DescribeTimeToLiveResponse;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import java.util.logging.Level;
import java.util.logging.Logger;
public DescribeTimeToLiveResponse describeTTL(final String tableName, final Region region) {
final DescribeTimeToLiveRequest request =
DescribeTimeToLiveRequest.builder().tableName(tableName).build();
try (DynamoDbClient ddb = dynamoDbClient != null
? dynamoDbClient
: DynamoDbClient.builder().region(region).build()) {
return ddb.describeTimeToLive(request);
} catch (ResourceNotFoundException e) {
System.err.format(TABLE_NOT_FOUND_ERROR, tableName);
throw e;
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
throw e;
}
}
```
+ For API details, see [DescribeTimeToLive](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/DescribeTimeToLive) in *AWS SDK for Java 2.x API Reference*.
### `GetItem`
The following code example shows how to use `GetItem`.
**SDK for Java 2.x**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/dynamodb#code-examples).
Gets an item from a table by using the DynamoDbClient.
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.GetItemRequest;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
/**
* Before running this Java V2 code example, set up your development
* environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*
* To get an item from an Amazon DynamoDB table using the AWS SDK for Java V2,
* its better practice to use the
* Enhanced Client, see the EnhancedGetItem example.
*/
public class GetItem {
public static void main(String[] args) {
final String usage = """
Usage:
Where:
tableName - The Amazon DynamoDB table from which an item is retrieved (for example, Music3).\s
key - The key used in the Amazon DynamoDB table (for example, Artist).\s
keyval - The key value that represents the item to get (for example, Famous Band).
""";
if (args.length != 3) {
System.out.println(usage);
System.exit(1);
}
String tableName = args[0];
String key = args[1];
String keyVal = args[2];
System.out.format("Retrieving item \"%s\" from \"%s\"\n", keyVal, tableName);
Region region = Region.US_EAST_1;
DynamoDbClient ddb = DynamoDbClient.builder()
.region(region)
.build();
getDynamoDBItem(ddb, tableName, key, keyVal);
ddb.close();
}
public static void getDynamoDBItem(DynamoDbClient ddb, String tableName, String key, String keyVal) {
HashMap keyToGet = new HashMap<>();
keyToGet.put(key, AttributeValue.builder()
.s(keyVal)
.build());
GetItemRequest request = GetItemRequest.builder()
.key(keyToGet)
.tableName(tableName)
.build();
try {
// If there is no matching item, GetItem does not return any data.
Map returnedItem = ddb.getItem(request).item();
if (returnedItem.isEmpty())
System.out.format("No item found with the key %s!\n", key);
else {
Set keys = returnedItem.keySet();
System.out.println("Amazon DynamoDB table attributes: \n");
for (String key1 : keys) {
System.out.format("%s: %s\n", key1, returnedItem.get(key1).toString());
}
}
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
}
}
```
+ For API details, see [GetItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/GetItem) in *AWS SDK for Java 2.x API Reference*.
### `ListTables`
The following code example shows how to use `ListTables`.
**SDK for Java 2.x**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/dynamodb#code-examples).
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ListTablesRequest;
import software.amazon.awssdk.services.dynamodb.model.ListTablesResponse;
import java.util.List;
/**
* Before running this Java V2 code example, set up your development
* environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*/
public class ListTables {
public static void main(String[] args) {
System.out.println("Listing your Amazon DynamoDB tables:\n");
Region region = Region.US_EAST_1;
DynamoDbClient ddb = DynamoDbClient.builder()
.region(region)
.build();
listAllTables(ddb);
ddb.close();
}
public static void listAllTables(DynamoDbClient ddb) {
boolean moreTables = true;
String lastName = null;
while (moreTables) {
try {
ListTablesResponse response = null;
if (lastName == null) {
ListTablesRequest request = ListTablesRequest.builder().build();
response = ddb.listTables(request);
} else {
ListTablesRequest request = ListTablesRequest.builder()
.exclusiveStartTableName(lastName).build();
response = ddb.listTables(request);
}
List tableNames = response.tableNames();
if (tableNames.size() > 0) {
for (String curName : tableNames) {
System.out.format("* %s\n", curName);
}
} else {
System.out.println("No tables found!");
System.exit(0);
}
lastName = response.lastEvaluatedTableName();
if (lastName == null) {
moreTables = false;
}
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
}
System.out.println("\nDone!");
}
}
```
+ For API details, see [ListTables](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/ListTables) in *AWS SDK for Java 2.x API Reference*.
### `PutItem`
The following code example shows how to use `PutItem`.
**SDK for Java 2.x**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/dynamodb#code-examples).
Puts an item into a table using [DynamoDbClient](http://docs.aws.amazon.com/sdk-for-java/latest/reference/software/amazon/awssdk/services/dynamodb/DynamoDbClient.html).
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.PutItemRequest;
import software.amazon.awssdk.services.dynamodb.model.PutItemResponse;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import java.util.HashMap;
/**
* Before running this Java V2 code example, set up your development
* environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*
* To place items into an Amazon DynamoDB table using the AWS SDK for Java V2,
* its better practice to use the
* Enhanced Client. See the EnhancedPutItem example.
*/
public class PutItem {
public static void main(String[] args) {
final String usage = """
Usage:
Where:
tableName - The Amazon DynamoDB table in which an item is placed (for example, Music3).
key - The key used in the Amazon DynamoDB table (for example, Artist).
keyval - The key value that represents the item to get (for example, Famous Band).
albumTitle - The Album title (for example, AlbumTitle).
AlbumTitleValue - The name of the album (for example, Songs About Life ).
Awards - The awards column (for example, Awards).
AwardVal - The value of the awards (for example, 10).
SongTitle - The song title (for example, SongTitle).
SongTitleVal - The value of the song title (for example, Happy Day).
**Warning** This program will place an item that you specify into a table!
""";
if (args.length != 9) {
System.out.println(usage);
System.exit(1);
}
String tableName = args[0];
String key = args[1];
String keyVal = args[2];
String albumTitle = args[3];
String albumTitleValue = args[4];
String awards = args[5];
String awardVal = args[6];
String songTitle = args[7];
String songTitleVal = args[8];
Region region = Region.US_EAST_1;
DynamoDbClient ddb = DynamoDbClient.builder()
.region(region)
.build();
putItemInTable(ddb, tableName, key, keyVal, albumTitle, albumTitleValue, awards, awardVal, songTitle,
songTitleVal);
System.out.println("Done!");
ddb.close();
}
public static void putItemInTable(DynamoDbClient ddb,
String tableName,
String key,
String keyVal,
String albumTitle,
String albumTitleValue,
String awards,
String awardVal,
String songTitle,
String songTitleVal) {
HashMap itemValues = new HashMap<>();
itemValues.put(key, AttributeValue.builder().s(keyVal).build());
itemValues.put(songTitle, AttributeValue.builder().s(songTitleVal).build());
itemValues.put(albumTitle, AttributeValue.builder().s(albumTitleValue).build());
itemValues.put(awards, AttributeValue.builder().s(awardVal).build());
PutItemRequest request = PutItemRequest.builder()
.tableName(tableName)
.item(itemValues)
.build();
try {
PutItemResponse response = ddb.putItem(request);
System.out.println(tableName + " was successfully updated. The request id is "
+ response.responseMetadata().requestId());
} catch (ResourceNotFoundException e) {
System.err.format("Error: The Amazon DynamoDB table \"%s\" can't be found.\n", tableName);
System.err.println("Be sure that it exists and that you've typed its name correctly!");
System.exit(1);
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
}
}
```
+ For API details, see [PutItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/PutItem) in *AWS SDK for Java 2.x API Reference*.
### `Query`
The following code example shows how to use `Query`.
**SDK for Java 2.x**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/dynamodb#code-examples).
Queries a table by using [DynamoDbClient](http://docs.aws.amazon.com/sdk-for-java/latest/reference/software/amazon/awssdk/services/dynamodb/DynamoDbClient.html).
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import java.util.HashMap;
/**
* Before running this Java V2 code example, set up your development
* environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*
* To query items from an Amazon DynamoDB table using the AWS SDK for Java V2,
* its better practice to use the
* Enhanced Client. See the EnhancedQueryRecords example.
*/
public class Query {
public static void main(String[] args) {
final String usage = """
Usage:
Where:
tableName - The Amazon DynamoDB table to put the item in (for example, Music3).
partitionKeyName - The partition key name of the Amazon DynamoDB table (for example, Artist).
partitionKeyVal - The value of the partition key that should match (for example, Famous Band).
""";
if (args.length != 3) {
System.out.println(usage);
System.exit(1);
}
String tableName = args[0];
String partitionKeyName = args[1];
String partitionKeyVal = args[2];
// For more information about an alias, see:
// https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.ExpressionAttributeNames.html
String partitionAlias = "#a";
System.out.format("Querying %s", tableName);
System.out.println("");
Region region = Region.US_EAST_1;
DynamoDbClient ddb = DynamoDbClient.builder()
.region(region)
.build();
int count = queryTable(ddb, tableName, partitionKeyName, partitionKeyVal, partitionAlias);
System.out.println("There were " + count + " record(s) returned");
ddb.close();
}
public static int queryTable(DynamoDbClient ddb, String tableName, String partitionKeyName, String partitionKeyVal,
String partitionAlias) {
// Set up an alias for the partition key name in case it's a reserved word.
HashMap attrNameAlias = new HashMap();
attrNameAlias.put(partitionAlias, partitionKeyName);
// Set up mapping of the partition name with the value.
HashMap attrValues = new HashMap<>();
attrValues.put(":" + partitionKeyName, AttributeValue.builder()
.s(partitionKeyVal)
.build());
QueryRequest queryReq = QueryRequest.builder()
.tableName(tableName)
.keyConditionExpression(partitionAlias + " = :" + partitionKeyName)
.expressionAttributeNames(attrNameAlias)
.expressionAttributeValues(attrValues)
.build();
try {
QueryResponse response = ddb.query(queryReq);
return response.count();
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
return -1;
}
}
```
Queries a table by using `DynamoDbClient` and a secondary index.
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import java.util.HashMap;
import java.util.Map;
/**
* Before running this Java V2 code example, set up your development
* environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*
* Create the Movies table by running the Scenario example and loading the Movie
* data from the JSON file. Next create a secondary
* index for the Movies table that uses only the year column. Name the index
* **year-index**. For more information, see:
*
* https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GSI.html
*/
public class QueryItemsUsingIndex {
public static void main(String[] args) {
String tableName = "Movies";
Region region = Region.US_EAST_1;
DynamoDbClient ddb = DynamoDbClient.builder()
.region(region)
.build();
queryIndex(ddb, tableName);
ddb.close();
}
public static void queryIndex(DynamoDbClient ddb, String tableName) {
try {
Map expressionAttributesNames = new HashMap<>();
expressionAttributesNames.put("#year", "year");
Map expressionAttributeValues = new HashMap<>();
expressionAttributeValues.put(":yearValue", AttributeValue.builder().n("2013").build());
QueryRequest request = QueryRequest.builder()
.tableName(tableName)
.indexName("year-index")
.keyConditionExpression("#year = :yearValue")
.expressionAttributeNames(expressionAttributesNames)
.expressionAttributeValues(expressionAttributeValues)
.build();
System.out.println("=== Movie Titles ===");
QueryResponse response = ddb.query(request);
response.items()
.forEach(movie -> System.out.println(movie.get("title").s()));
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
}
}
```
+ For API details, see [Query](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/Query) in *AWS SDK for Java 2.x API Reference*.
### `Scan`
The following code example shows how to use `Scan`.
**SDK for Java 2.x**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/dynamodb#code-examples).
Scans an Amazon DynamoDB table using [DynamoDbClient](http://docs.aws.amazon.com/sdk-for-java/latest/reference/software/amazon/awssdk/services/dynamodb/DynamoDbClient.html).
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ScanRequest;
import software.amazon.awssdk.services.dynamodb.model.ScanResponse;
import java.util.Map;
import java.util.Set;
/**
* Before running this Java V2 code example, set up your development
* environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*
* To scan items from an Amazon DynamoDB table using the AWS SDK for Java V2,
* its better practice to use the
* Enhanced Client, See the EnhancedScanRecords example.
*/
public class DynamoDBScanItems {
public static void main(String[] args) {
final String usage = """
Usage:
Where:
tableName - The Amazon DynamoDB table to get information from (for example, Music3).
""";
if (args.length != 1) {
System.out.println(usage);
System.exit(1);
}
String tableName = args[0];
Region region = Region.US_EAST_1;
DynamoDbClient ddb = DynamoDbClient.builder()
.region(region)
.build();
scanItems(ddb, tableName);
ddb.close();
}
public static void scanItems(DynamoDbClient ddb, String tableName) {
try {
ScanRequest scanRequest = ScanRequest.builder()
.tableName(tableName)
.build();
ScanResponse response = ddb.scan(scanRequest);
for (Map item : response.items()) {
Set keys = item.keySet();
for (String key : keys) {
System.out.println("The key name is " + key + "\n");
System.out.println("The value is " + item.get(key).s());
}
}
} catch (DynamoDbException e) {
e.printStackTrace();
System.exit(1);
}
}
}
```
+ For API details, see [Scan](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/Scan) in *AWS SDK for Java 2.x API Reference*.
### `UpdateItem`
The following code example shows how to use `UpdateItem`.
**SDK for Java 2.x**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/dynamodb#code-examples).
Updates an item in a table using [DynamoDbClient](http://docs.aws.amazon.com/sdk-for-java/latest/reference/software/amazon/awssdk/services/dynamodb/DynamoDbClient.html).
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.AttributeAction;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.AttributeValueUpdate;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemRequest;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import java.util.HashMap;
/**
* Before running this Java V2 code example, set up your development
* environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*
* To update an Amazon DynamoDB table using the AWS SDK for Java V2, its better
* practice to use the
* Enhanced Client, See the EnhancedModifyItem example.
*/
public class UpdateItem {
public static void main(String[] args) {
final String usage = """
Usage:
Where:
tableName - The Amazon DynamoDB table (for example, Music3).
key - The name of the key in the table (for example, Artist).
keyVal - The value of the key (for example, Famous Band).
name - The name of the column where the value is updated (for example, Awards).
updateVal - The value used to update an item (for example, 14).
Example:
UpdateItem Music3 Artist Famous Band Awards 14
""";
if (args.length != 5) {
System.out.println(usage);
System.exit(1);
}
String tableName = args[0];
String key = args[1];
String keyVal = args[2];
String name = args[3];
String updateVal = args[4];
Region region = Region.US_EAST_1;
DynamoDbClient ddb = DynamoDbClient.builder()
.region(region)
.build();
updateTableItem(ddb, tableName, key, keyVal, name, updateVal);
ddb.close();
}
public static void updateTableItem(DynamoDbClient ddb,
String tableName,
String key,
String keyVal,
String name,
String updateVal) {
HashMap itemKey = new HashMap<>();
itemKey.put(key, AttributeValue.builder()
.s(keyVal)
.build());
HashMap updatedValues = new HashMap<>();
updatedValues.put(name, AttributeValueUpdate.builder()
.value(AttributeValue.builder().s(updateVal).build())
.action(AttributeAction.PUT)
.build());
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(itemKey)
.attributeUpdates(updatedValues)
.build();
try {
ddb.updateItem(request);
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
System.out.println("The Amazon DynamoDB table was updated!");
}
}
```
+ For API details, see [UpdateItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/UpdateItem) in *AWS SDK for Java 2.x API Reference*.
### `UpdateTimeToLive`
The following code example shows how to use `UpdateTimeToLive`.
**SDK for Java 2.x**
Enable TTL on an existing DynamoDB table using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import software.amazon.awssdk.services.dynamodb.model.TimeToLiveSpecification;
import software.amazon.awssdk.services.dynamodb.model.UpdateTimeToLiveRequest;
import software.amazon.awssdk.services.dynamodb.model.UpdateTimeToLiveResponse;
import java.util.logging.Level;
import java.util.logging.Logger;
public UpdateTimeToLiveResponse enableTTL(final String tableName, final String attributeName, final Region region) {
final TimeToLiveSpecification ttlSpec = TimeToLiveSpecification.builder()
.attributeName(attributeName)
.enabled(true)
.build();
final UpdateTimeToLiveRequest request = UpdateTimeToLiveRequest.builder()
.tableName(tableName)
.timeToLiveSpecification(ttlSpec)
.build();
try (DynamoDbClient ddb = dynamoDbClient != null
? dynamoDbClient
: DynamoDbClient.builder().region(region).build()) {
return ddb.updateTimeToLive(request);
} catch (ResourceNotFoundException e) {
System.err.format(TABLE_NOT_FOUND_ERROR, tableName);
throw e;
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
throw e;
}
}
```
Disable TTL on an existing DynamoDB table using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import software.amazon.awssdk.services.dynamodb.model.TimeToLiveSpecification;
import software.amazon.awssdk.services.dynamodb.model.UpdateTimeToLiveRequest;
import software.amazon.awssdk.services.dynamodb.model.UpdateTimeToLiveResponse;
import java.util.logging.Level;
import java.util.logging.Logger;
public UpdateTimeToLiveResponse disableTTL(
final String tableName, final String attributeName, final Region region) {
final TimeToLiveSpecification ttlSpec = TimeToLiveSpecification.builder()
.attributeName(attributeName)
.enabled(false)
.build();
final UpdateTimeToLiveRequest request = UpdateTimeToLiveRequest.builder()
.tableName(tableName)
.timeToLiveSpecification(ttlSpec)
.build();
try (DynamoDbClient ddb = dynamoDbClient != null
? dynamoDbClient
: DynamoDbClient.builder().region(region).build()) {
return ddb.updateTimeToLive(request);
} catch (ResourceNotFoundException e) {
System.err.format(TABLE_NOT_FOUND_ERROR, tableName);
throw e;
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
throw e;
}
}
```
+ For API details, see [UpdateTimeToLive](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/UpdateTimeToLive) in *AWS SDK for Java 2.x API Reference*.
## Scenarios
### Build an app to submit data to a DynamoDB table
The following code example shows how to build an application that submits data to an Amazon DynamoDB table and notifies you when a user updates the table.
**SDK for Java 2.x**
Shows how to create a dynamic web application that submits data using the Amazon DynamoDB Java API and sends a text message using the Amazon Simple Notification Service Java API.
For complete source code and instructions on how to set up and run, see the full example on [GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/usecases/creating_first_project).
**Services used in this example**
+ DynamoDB
+ Amazon SNS
### Compare multiple values with a single attribute
The following code example shows how to compare multiple values with a single attribute in DynamoDB.
+ Use the IN operator to compare multiple values with a single attribute.
+ Compare the IN operator with multiple OR conditions.
+ Understand the performance and expression complexity benefits of using IN.
**SDK for Java 2.x**
Compare multiple values with a single attribute in DynamoDB using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import software.amazon.awssdk.services.dynamodb.model.ScanRequest;
import software.amazon.awssdk.services.dynamodb.model.ScanResponse;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
/**
* Queries a table using the IN operator to compare multiple values with a single attribute.
*
* This method demonstrates how to use the IN operator in a filter expression
* to match an attribute against multiple values.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param partitionKeyName The name of the partition key attribute
* @param partitionKeyValue The value of the partition key to query
* @param attributeName The name of the attribute to compare
* @param valuesList List of values to compare against
* @return The query response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static QueryResponse compareMultipleValues(
DynamoDbClient dynamoDbClient,
String tableName,
String partitionKeyName,
AttributeValue partitionKeyValue,
String attributeName,
List valuesList) {
// Create expression attribute names
Map expressionAttributeNames = new HashMap<>();
expressionAttributeNames.put("#pkName", partitionKeyName);
expressionAttributeNames.put("#attrName", attributeName);
// Create expression attribute values
Map expressionAttributeValues = new HashMap<>();
expressionAttributeValues.put(":pkValue", partitionKeyValue);
// Add values for IN operator
for (int i = 0; i < valuesList.size(); i++) {
expressionAttributeValues.put(":val" + i, valuesList.get(i));
}
// Build the IN clause
StringBuilder inClause = new StringBuilder();
for (int i = 0; i < valuesList.size(); i++) {
if (i > 0) {
inClause.append(", ");
}
inClause.append(":val").append(i);
}
// Define the query parameters
QueryRequest request = QueryRequest.builder()
.tableName(tableName)
.keyConditionExpression("#pkName = :pkValue")
.filterExpression("#attrName IN (" + inClause.toString() + ")")
.expressionAttributeNames(expressionAttributeNames)
.expressionAttributeValues(expressionAttributeValues)
.build();
// Perform the query operation
return dynamoDbClient.query(request);
}
/**
* Queries a table using multiple OR conditions to compare multiple values with a single attribute.
*
* This method demonstrates the alternative approach to using the IN operator,
* by using multiple OR conditions.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param partitionKeyName The name of the partition key attribute
* @param partitionKeyValue The value of the partition key to query
* @param attributeName The name of the attribute to compare
* @param valuesList List of values to compare against
* @return The query response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static QueryResponse compareWithOrConditions(
DynamoDbClient dynamoDbClient,
String tableName,
String partitionKeyName,
AttributeValue partitionKeyValue,
String attributeName,
List valuesList) {
// Create expression attribute names
Map expressionAttributeNames = new HashMap<>();
expressionAttributeNames.put("#pkName", partitionKeyName);
expressionAttributeNames.put("#attrName", attributeName);
// Create expression attribute values
Map expressionAttributeValues = new HashMap<>();
expressionAttributeValues.put(":pkValue", partitionKeyValue);
// Add values for OR conditions
for (int i = 0; i < valuesList.size(); i++) {
expressionAttributeValues.put(":val" + i, valuesList.get(i));
}
// Build the OR conditions
StringBuilder orConditions = new StringBuilder();
for (int i = 0; i < valuesList.size(); i++) {
if (i > 0) {
orConditions.append(" OR ");
}
orConditions.append("#attrName = :val").append(i);
}
// Define the query parameters
QueryRequest request = QueryRequest.builder()
.tableName(tableName)
.keyConditionExpression("#pkName = :pkValue")
.filterExpression(orConditions.toString())
.expressionAttributeNames(expressionAttributeNames)
.expressionAttributeValues(expressionAttributeValues)
.build();
// Perform the query operation
return dynamoDbClient.query(request);
}
/**
* Compares the performance of using the IN operator versus multiple OR conditions.
*
* This method demonstrates the performance difference between using the IN operator
* and using multiple OR conditions.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param partitionKeyName The name of the partition key attribute
* @param partitionKeyValue The value of the partition key to query
* @param attributeName The name of the attribute to compare
* @param valuesList List of values to compare against
* @return Map containing the performance comparison results
*/
public static Map comparePerformance(
DynamoDbClient dynamoDbClient,
String tableName,
String partitionKeyName,
AttributeValue partitionKeyValue,
String attributeName,
List valuesList) {
Map results = new HashMap<>();
try {
// Measure performance of IN operator
long inStartTime = System.nanoTime();
QueryResponse inResponse = compareMultipleValues(
dynamoDbClient, tableName, partitionKeyName, partitionKeyValue, attributeName, valuesList);
long inEndTime = System.nanoTime();
long inDuration = inEndTime - inStartTime;
// Measure performance of OR conditions
long orStartTime = System.nanoTime();
QueryResponse orResponse = compareWithOrConditions(
dynamoDbClient, tableName, partitionKeyName, partitionKeyValue, attributeName, valuesList);
long orEndTime = System.nanoTime();
long orDuration = orEndTime - orStartTime;
// Record results
results.put("inOperatorDuration", inDuration);
results.put("orConditionsDuration", orDuration);
results.put("inOperatorItems", inResponse.count());
results.put("orConditionsItems", orResponse.count());
results.put("inOperatorExpression", "IN operator with " + valuesList.size() + " values");
results.put("orConditionsExpression", valuesList.size() + " OR conditions");
results.put("success", true);
} catch (DynamoDbException e) {
results.put("success", false);
results.put("error", e.getMessage());
}
return results;
}
/**
* Scans a table using the IN operator with a large number of values.
*
* This method demonstrates how to use the IN operator with a large number of values,
* which can help stay within the 300 operator limit.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param attributeName The name of the attribute to compare
* @param valuesList List of values to compare against
* @return The scan response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static ScanResponse scanWithLargeInClause(
DynamoDbClient dynamoDbClient, String tableName, String attributeName, List valuesList) {
// Create expression attribute names
Map expressionAttributeNames = new HashMap<>();
expressionAttributeNames.put("#attrName", attributeName);
// Create expression attribute values
Map expressionAttributeValues = new HashMap<>();
// Add values for IN operator
for (int i = 0; i < valuesList.size(); i++) {
expressionAttributeValues.put(":val" + i, valuesList.get(i));
}
// Build the IN clause
StringBuilder inClause = new StringBuilder();
for (int i = 0; i < valuesList.size(); i++) {
if (i > 0) {
inClause.append(", ");
}
inClause.append(":val").append(i);
}
// Define the scan parameters
ScanRequest request = ScanRequest.builder()
.tableName(tableName)
.filterExpression("#attrName IN (" + inClause.toString() + ")")
.expressionAttributeNames(expressionAttributeNames)
.expressionAttributeValues(expressionAttributeValues)
.build();
// Perform the scan operation
return dynamoDbClient.scan(request);
}
/**
* Generates a list of sample values for testing.
*
* Helper method to generate a list of sample values for testing.
*
* @param valueType The type of values to generate (string, number, or boolean)
* @param count The number of values to generate
* @return List of generated attribute values
*/
public static List generateSampleValues(String valueType, int count) {
List values = new ArrayList<>();
for (int i = 0; i < count; i++) {
AttributeValue value;
switch (valueType.toLowerCase(Locale.ROOT)) {
case "string":
value = AttributeValue.builder().s("Value" + i).build();
break;
case "number":
value = AttributeValue.builder().n(String.valueOf(i)).build();
break;
case "boolean":
value = AttributeValue.builder().bool(i % 2 == 0).build();
break;
default:
throw new IllegalArgumentException("Unsupported value type: " + valueType);
}
values.add(value);
}
return values;
}
```
Example usage of comparing multiple values with AWS SDK for Java 2.x.
```
public static void exampleUsage(DynamoDbClient dynamoDbClient, String tableName) {
System.out.println("Demonstrating how to compare multiple values with a single attribute in DynamoDB");
try {
// Example 1: Using the IN operator
System.out.println("\nExample 1: Using the IN operator");
List categories = List.of(
AttributeValue.builder().s("Electronics").build(),
AttributeValue.builder().s("Computers").build(),
AttributeValue.builder().s("Accessories").build());
QueryResponse inResponse = compareMultipleValues(
dynamoDbClient,
tableName,
"Department",
AttributeValue.builder().s("Retail").build(),
"Category",
categories);
System.out.println("Found " + inResponse.count() + " items using IN operator");
System.out.println("Items: " + inResponse.items());
// Example 2: Using multiple OR conditions
System.out.println("\nExample 2: Using multiple OR conditions");
QueryResponse orResponse = compareWithOrConditions(
dynamoDbClient,
tableName,
"Department",
AttributeValue.builder().s("Retail").build(),
"Category",
categories);
System.out.println("Found " + orResponse.count() + " items using OR conditions");
System.out.println("Items: " + orResponse.items());
// Example 3: Performance comparison
System.out.println("\nExample 3: Performance comparison");
Map perfComparison = comparePerformance(
dynamoDbClient,
tableName,
"Department",
AttributeValue.builder().s("Retail").build(),
"Category",
categories);
if ((boolean) perfComparison.get("success")) {
System.out.println("IN operator duration: " + perfComparison.get("inOperatorDuration") + " ns");
System.out.println("OR conditions duration: " + perfComparison.get("orConditionsDuration") + " ns");
System.out.println("IN operator found " + perfComparison.get("inOperatorItems") + " items");
System.out.println("OR conditions found " + perfComparison.get("orConditionsItems") + " items");
System.out.println("Expression complexity comparison:");
System.out.println(" IN operator: " + perfComparison.get("inOperatorExpression"));
System.out.println(" OR conditions: " + perfComparison.get("orConditionsExpression"));
} else {
System.out.println("Performance comparison failed: " + perfComparison.get("error"));
}
// Example 4: Using IN with a large number of values
System.out.println("\nExample 4: Using IN with a large number of values");
List productIds = generateSampleValues("string", 20);
ScanResponse largeInResponse = scanWithLargeInClause(dynamoDbClient, tableName, "ProductId", productIds);
System.out.println(
"Found " + largeInResponse.count() + " items using IN with " + productIds.size() + " values");
// Explain the benefits of using IN
System.out.println("\nKey points about using the IN operator in DynamoDB:");
System.out.println("1. The IN operator allows comparing a single attribute against multiple values");
System.out.println("2. IN is more concise than using multiple OR conditions");
System.out.println("3. IN counts as only 1 operator regardless of the number of values");
System.out.println("4. Multiple OR conditions count as 1 operator per condition plus 1 per OR");
System.out.println("5. Using IN helps stay within the 300 operator limit for complex expressions");
System.out.println("6. IN can be used in filter expressions and condition expressions");
System.out.println("7. The IN operator supports up to 100 comparison values");
} catch (DynamoDbException e) {
System.err.println("Error: " + e.getMessage());
e.printStackTrace();
}
}
```
+ For API details, see the following topics in *AWS SDK for Java 2.x API Reference*.
+ [Query](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/Query)
+ [Scan](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/Scan)
### Conditionally update an item's TTL
The following code example shows how to conditionally update an item's TTL.
**SDK for Java 2.x**
Update TTL on on an existing DynamoDB Item in a table, with a condition.
```
package com.amazon.samplelib.ttl;
import com.amazon.samplelib.CodeSampleUtils;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.ConditionalCheckFailedException;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemRequest;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemResponse;
import java.util.Map;
import java.util.Optional;
/**
* Updates an item in a DynamoDB table with TTL attributes using a conditional expression.
* This class demonstrates how to conditionally update TTL expiration timestamps.
*/
public class UpdateTTLConditional {
private static final String USAGE =
"""
Usage:
Where:
tableName - The Amazon DynamoDB table being queried.
primaryKey - The name of the primary key. Also known as the hash or partition key.
sortKey - The name of the sort key. Also known as the range attribute.
region (optional) - The AWS region that the Amazon DynamoDB table is located in. (Default: us-east-1)
""";
private static final int DAYS_TO_EXPIRE = 90;
private static final int SECONDS_PER_DAY = 24 * 60 * 60;
private static final String PRIMARY_KEY_ATTR = "primaryKey";
private static final String SORT_KEY_ATTR = "sortKey";
private static final String UPDATED_AT_ATTR = "updatedAt";
private static final String EXPIRE_AT_ATTR = "expireAt";
private static final String UPDATE_EXPRESSION = "SET " + UPDATED_AT_ATTR + "=:c, " + EXPIRE_AT_ATTR + "=:e";
private static final String CONDITION_EXPRESSION = "attribute_exists(" + PRIMARY_KEY_ATTR + ")";
private static final String SUCCESS_MESSAGE = "%s UpdateItem operation with TTL successful.";
private static final String CONDITION_FAILED_MESSAGE = "Condition check failed. Item does not exist.";
private static final String TABLE_NOT_FOUND_ERROR = "Error: The Amazon DynamoDB table \"%s\" can't be found.";
private final DynamoDbClient dynamoDbClient;
/**
* Constructs an UpdateTTLConditional with a default DynamoDB client.
*/
public UpdateTTLConditional() {
this.dynamoDbClient = null;
}
/**
* Constructs an UpdateTTLConditional with the specified DynamoDB client.
*
* @param dynamoDbClient The DynamoDB client to use
*/
public UpdateTTLConditional(final DynamoDbClient dynamoDbClient) {
this.dynamoDbClient = dynamoDbClient;
}
/**
* Main method to demonstrate conditionally updating an item with TTL.
*
* @param args Command line arguments
*/
public static void main(final String[] args) {
try {
int result = new UpdateTTLConditional().processArgs(args);
System.exit(result);
} catch (Exception e) {
System.err.println(e.getMessage());
System.exit(1);
}
}
/**
* Process command line arguments and conditionally update an item with TTL.
*
* @param args Command line arguments
* @return 0 if successful, non-zero otherwise
* @throws ResourceNotFoundException If the table doesn't exist
* @throws DynamoDbException If an error occurs during the operation
* @throws IllegalArgumentException If arguments are invalid
*/
public int processArgs(final String[] args) {
// Argument validation (remove or replace this line when reusing this code)
CodeSampleUtils.validateArgs(args, new int[] {3, 4}, USAGE);
final String tableName = args[0];
final String primaryKey = args[1];
final String sortKey = args[2];
final Region region = Optional.ofNullable(args.length > 3 ? args[3] : null)
.map(Region::of)
.orElse(Region.US_EAST_1);
// Get current time in epoch second format
final long currentTime = System.currentTimeMillis() / 1000;
// Calculate expiration time 90 days from now in epoch second format
final long expireDate = currentTime + (DAYS_TO_EXPIRE * SECONDS_PER_DAY);
// Create the key map for the item to update
final Map keyMap = Map.of(
PRIMARY_KEY_ATTR, AttributeValue.builder().s(primaryKey).build(),
SORT_KEY_ATTR, AttributeValue.builder().s(sortKey).build());
// Create the expression attribute values
final Map expressionAttributeValues = Map.of(
":c", AttributeValue.builder().n(String.valueOf(currentTime)).build(),
":e", AttributeValue.builder().n(String.valueOf(expireDate)).build());
final UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(keyMap)
.updateExpression(UPDATE_EXPRESSION)
.conditionExpression(CONDITION_EXPRESSION)
.expressionAttributeValues(expressionAttributeValues)
.build();
try (DynamoDbClient ddb = dynamoDbClient != null
? dynamoDbClient
: DynamoDbClient.builder().region(region).build()) {
final UpdateItemResponse response = ddb.updateItem(request);
System.out.println(String.format(SUCCESS_MESSAGE, tableName));
return 0;
} catch (ConditionalCheckFailedException e) {
System.err.println(CONDITION_FAILED_MESSAGE);
throw e;
} catch (ResourceNotFoundException e) {
System.err.format(TABLE_NOT_FOUND_ERROR, tableName);
throw e;
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
throw e;
}
}
}
```
+ For API details, see [UpdateItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/UpdateItem) in *AWS SDK for Java 2.x API Reference*.
### Count expression operators
The following code example shows how to count expression operators in DynamoDB.
+ Understand DynamoDB's 300 operator limit.
+ Count operators in complex expressions.
+ Optimize expressions to stay within limits.
**SDK for Java 2.x**
Demonstrate expression operator counting using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemRequest;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemResponse;
import java.util.HashMap;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Creates a complex filter expression with a specified number of conditions.
*
* This method demonstrates how to generate a complex expression with
* a specific number of operators to test the 300 operator limit.
*
* @param conditionsCount Number of conditions to include
* @param useAnd Whether to use AND (true) or OR (false) between conditions
* @return Map containing the filter expression, attribute values, and operator count
*/
public static Map createComplexFilterExpression(int conditionsCount, boolean useAnd) {
// Initialize the expression parts and attribute values
StringBuilder filterExpression = new StringBuilder();
Map expressionAttributeValues = new HashMap<>();
// Generate the specified number of conditions
for (int i = 0; i < conditionsCount; i++) {
// Add the operator between conditions (except for the first one)
if (i > 0) {
filterExpression.append(useAnd ? " AND " : " OR ");
}
// Alternate between different comparison operators for variety
String valueKey = ":val" + i;
switch (i % 5) {
case 0:
filterExpression.append("attribute").append(i).append(" = ").append(valueKey);
expressionAttributeValues.put(
valueKey, AttributeValue.builder().s("value" + i).build());
break;
case 1:
filterExpression.append("attribute").append(i).append(" > ").append(valueKey);
expressionAttributeValues.put(
valueKey, AttributeValue.builder().n(String.valueOf(i)).build());
break;
case 2:
filterExpression.append("attribute").append(i).append(" < ").append(valueKey);
expressionAttributeValues.put(
valueKey,
AttributeValue.builder().n(String.valueOf(i * 10)).build());
break;
case 3:
filterExpression
.append("contains(attribute")
.append(i)
.append(", ")
.append(valueKey)
.append(")");
expressionAttributeValues.put(
valueKey, AttributeValue.builder().s("substring" + i).build());
break;
case 4:
filterExpression
.append("attribute_exists(attribute")
.append(i)
.append(")");
break;
default:
// This case will never be reached, but added to satisfy checkstyle
break;
}
}
// Calculate the operator count
// Each condition has 1 operator (=, >, <, contains, attribute_exists)
// Each AND or OR between conditions is 1 operator
int operatorCount = conditionsCount + (conditionsCount > 0 ? conditionsCount - 1 : 0);
// Create the result map
Map result = new HashMap<>();
result.put("filterExpression", filterExpression.toString());
result.put("expressionAttributeValues", expressionAttributeValues);
result.put("operatorCount", operatorCount);
return result;
}
/**
* Creates a complex update expression with a specified number of operations.
*
* This method demonstrates how to generate a complex update expression with
* a specific number of operators to test the 300 operator limit.
*
* @param operationsCount Number of operations to include
* @return Map containing the update expression, attribute values, and operator count
*/
public static Map createComplexUpdateExpression(int operationsCount) {
// Initialize the expression parts and attribute values
StringBuilder updateExpression = new StringBuilder("SET ");
Map expressionAttributeValues = new HashMap<>();
// Generate the specified number of SET operations
for (int i = 0; i < operationsCount; i++) {
// Add comma between operations (except for the first one)
if (i > 0) {
updateExpression.append(", ");
}
// Alternate between different types of SET operations
String valueKey = ":val" + i;
switch (i % 3) {
case 0:
// Simple assignment (1 operator: =)
updateExpression.append("attribute").append(i).append(" = ").append(valueKey);
expressionAttributeValues.put(
valueKey, AttributeValue.builder().s("value" + i).build());
break;
case 1:
// Addition (2 operators: = and +)
updateExpression
.append("attribute")
.append(i)
.append(" = attribute")
.append(i)
.append(" + ")
.append(valueKey);
expressionAttributeValues.put(
valueKey, AttributeValue.builder().n(String.valueOf(i)).build());
break;
case 2:
// Conditional assignment with if_not_exists (2 operators: = and if_not_exists)
updateExpression
.append("attribute")
.append(i)
.append(" = if_not_exists(attribute")
.append(i)
.append(", ")
.append(valueKey)
.append(")");
expressionAttributeValues.put(
valueKey,
AttributeValue.builder().n(String.valueOf(i * 10)).build());
break;
default:
// This case will never be reached, but added to satisfy checkstyle
break;
}
}
// Calculate the operator count
// Each operation has 1-2 operators as noted above
int operatorCount = 0;
for (int i = 0; i < operationsCount; i++) {
operatorCount += (i % 3 == 0) ? 1 : 2;
}
// Create the result map
Map result = new HashMap<>();
result.put("updateExpression", updateExpression.toString());
result.put("expressionAttributeValues", expressionAttributeValues);
result.put("operatorCount", operatorCount);
return result;
}
/**
* Test the operator limit by attempting an operation with a complex expression.
*
* This method demonstrates what happens when an expression approaches or
* exceeds the 300 operator limit.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to update
* @param operatorCount Target number of operators to include
* @return Map containing the result of the operation attempt
*/
public static Map testOperatorLimit(
DynamoDbClient dynamoDbClient, String tableName, Map key, int operatorCount) {
// Create a complex update expression with the specified operator count
Map expressionData =
createComplexUpdateExpression((int) Math.ceil(operatorCount / 1.5)); // Adjust to get close to target count
String updateExpression = (String) expressionData.get("updateExpression");
@SuppressWarnings("unchecked")
Map expressionAttributeValues =
(Map) expressionData.get("expressionAttributeValues");
int actualCount = (int) expressionData.get("operatorCount");
System.out.println("Generated update expression with approximately " + actualCount + " operators");
// Define the update parameters
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression(updateExpression)
.expressionAttributeValues(expressionAttributeValues)
.returnValues("UPDATED_NEW")
.build();
try {
// Attempt the update operation
UpdateItemResponse response = dynamoDbClient.updateItem(request);
Map result = new HashMap<>();
result.put("success", true);
result.put("message", "Operation succeeded with " + actualCount + " operators");
result.put("data", response);
return result;
} catch (DynamoDbException e) {
// Check if the error is due to exceeding the operator limit
if (e.getMessage().contains("too many operators")) {
Map result = new HashMap<>();
result.put("success", false);
result.put("message", "Operation failed: " + e.getMessage());
result.put("operatorCount", actualCount);
return result;
}
// Return other errors
Map result = new HashMap<>();
result.put("success", false);
result.put("message", "Operation failed: " + e.getMessage());
result.put("error", e);
return result;
}
}
/**
* Break down a complex expression into multiple simpler operations.
*
* This method demonstrates how to handle expressions that would exceed
* the 300 operator limit by breaking them into multiple operations.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to update
* @param totalOperations Total number of operations to perform
* @return Map containing the results of the operations
*/
public static Map breakDownComplexExpression(
DynamoDbClient dynamoDbClient, String tableName, Map key, int totalOperations) {
// Calculate how many operations we can safely include in each batch
// Using 150 as a conservative limit (well below 300)
final int operationsPerBatch = 100;
final int batchCount = (int) Math.ceil((double) totalOperations / operationsPerBatch);
System.out.println("Breaking down " + totalOperations + " operations into " + batchCount + " batches");
Map results = new HashMap<>();
results.put("totalBatches", batchCount);
Map> batchResults = new HashMap<>();
// Process each batch
for (int batch = 0; batch < batchCount; batch++) {
// Calculate the operations for this batch
int batchStart = batch * operationsPerBatch;
int batchEnd = Math.min(batchStart + operationsPerBatch, totalOperations);
int batchSize = batchEnd - batchStart;
System.out.println(
"Processing batch " + (batch + 1) + "/" + batchCount + " with " + batchSize + " operations");
// Create an update expression for this batch
Map expressionData = createComplexUpdateExpression(batchSize);
String updateExpression = (String) expressionData.get("updateExpression");
@SuppressWarnings("unchecked")
Map expressionAttributeValues =
(Map) expressionData.get("expressionAttributeValues");
int operatorCount = (int) expressionData.get("operatorCount");
// Define the update parameters
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression(updateExpression)
.expressionAttributeValues(expressionAttributeValues)
.returnValues("UPDATED_NEW")
.build();
try {
// Perform the update operation for this batch
UpdateItemResponse response = dynamoDbClient.updateItem(request);
Map batchResult = new HashMap<>();
batchResult.put("batch", batch + 1);
batchResult.put("success", true);
batchResult.put("operatorCount", operatorCount);
batchResult.put("attributes", response.attributes());
batchResults.put(batch, batchResult);
} catch (DynamoDbException e) {
Map batchResult = new HashMap<>();
batchResult.put("batch", batch + 1);
batchResult.put("success", false);
batchResult.put("operatorCount", operatorCount);
batchResult.put("error", e.getMessage());
batchResults.put(batch, batchResult);
// Continue with next batch instead of breaking
continue;
}
}
results.put("results", batchResults);
return results;
}
/**
* Count operators in a DynamoDB expression based on the rules in the documentation.
*
* This method demonstrates how operators are counted according to the
* DynamoDB documentation.
*
* @param expression The DynamoDB expression to analyze
* @return Map containing the breakdown of operator counts
*/
public static Map countOperatorsInExpression(String expression) {
// Initialize counters for different operator types
Map counts = new HashMap<>();
counts.put("comparisonOperators", 0);
counts.put("logicalOperators", 0);
counts.put("functions", 0);
counts.put("arithmeticOperators", 0);
counts.put("specialOperators", 0);
counts.put("total", 0);
// Count comparison operators (=, <>, <, <=, >, >=)
// This is a simplified approach and may not catch all cases
int comparisonCount = 0;
Pattern comparisonPattern = Pattern.compile("(=|<>|<=|>=|<|>)");
Matcher comparisonMatcher = comparisonPattern.matcher(expression);
while (comparisonMatcher.find()) {
comparisonCount++;
}
counts.put("comparisonOperators", comparisonCount);
// Count logical operators (AND, OR, NOT)
int andCount = countOccurrences(expression, "\\bAND\\b");
int orCount = countOccurrences(expression, "\\bOR\\b");
int notCount = countOccurrences(expression, "\\bNOT\\b");
counts.put("logicalOperators", andCount + orCount + notCount);
// Count functions (attribute_exists, attribute_not_exists, attribute_type, begins_with, contains, size)
int functionCount = countOccurrences(
expression,
"\\b(attribute_exists|attribute_not_exists|attribute_type|begins_with|contains|size|if_not_exists)\\(");
counts.put("functions", functionCount);
// Count arithmetic operators (+ and -)
// This is a simplified approach and may not catch all cases
int arithmeticCount = 0;
Pattern arithmeticPattern = Pattern.compile("[a-zA-Z0-9_)\\]]\\s*[\\+\\-]\\s*[a-zA-Z0-9_:(]");
Matcher arithmeticMatcher = arithmeticPattern.matcher(expression);
while (arithmeticMatcher.find()) {
arithmeticCount++;
}
counts.put("arithmeticOperators", arithmeticCount);
// Count special operators (BETWEEN, IN)
int betweenCount = countOccurrences(expression, "\\bBETWEEN\\b");
int inCount = countOccurrences(expression, "\\bIN\\b");
counts.put("specialOperators", betweenCount + inCount);
// Add extra operators for BETWEEN (each BETWEEN includes an AND)
int currentLogicalOps = counts.getOrDefault("logicalOperators", 0);
counts.put("logicalOperators", currentLogicalOps + betweenCount);
// Calculate total
int total = counts.getOrDefault("comparisonOperators", 0)
+ counts.getOrDefault("logicalOperators", 0)
+ counts.getOrDefault("functions", 0)
+ counts.getOrDefault("arithmeticOperators", 0)
+ counts.getOrDefault("specialOperators", 0);
counts.put("total", total);
return counts;
}
/**
* Helper method to count occurrences of a pattern in a string.
*
* @param text The text to search in
* @param regex The regular expression pattern to search for
* @return The number of occurrences
*/
private static int countOccurrences(String text, String regex) {
final Pattern pattern = Pattern.compile(regex);
final Matcher matcher = pattern.matcher(text);
int count = 0;
while (matcher.find()) {
count++;
}
return count;
}
```
Example usage of expression operator counting with AWS SDK for Java 2.x.
```
public static void exampleUsage(DynamoDbClient dynamoDbClient, String tableName) {
// Example key
Map key = new HashMap<>();
key.put("ProductId", AttributeValue.builder().s("P12345").build());
System.out.println("Demonstrating DynamoDB expression operator counting and the 300 operator limit");
try {
// Example 1: Analyze a simple expression
System.out.println("\nExample 1: Analyzing a simple expression");
String simpleExpression = "Price = :price AND Rating > :rating AND Category IN (:cat1, :cat2, :cat3)";
Map simpleCount = countOperatorsInExpression(simpleExpression);
System.out.println("Expression: " + simpleExpression);
System.out.println("Operator count breakdown:");
System.out.println("- Comparison operators: " + simpleCount.get("comparisonOperators"));
System.out.println("- Logical operators: " + simpleCount.get("logicalOperators"));
System.out.println("- Functions: " + simpleCount.get("functions"));
System.out.println("- Arithmetic operators: " + simpleCount.get("arithmeticOperators"));
System.out.println("- Special operators: " + simpleCount.get("specialOperators"));
System.out.println("- Total operators: " + simpleCount.get("total"));
// Example 2: Analyze a complex expression
System.out.println("\nExample 2: Analyzing a complex expression");
String complexExpression = "(attribute_exists(Category) AND Size BETWEEN :min AND :max) OR "
+ "(Price > :price AND contains(Description, :keyword) AND "
+ "(Rating >= :minRating OR Reviews > :minReviews))";
Map complexCount = countOperatorsInExpression(complexExpression);
System.out.println("Expression: " + complexExpression);
System.out.println("Operator count breakdown:");
System.out.println("- Comparison operators: " + complexCount.get("comparisonOperators"));
System.out.println("- Logical operators: " + complexCount.get("logicalOperators"));
System.out.println("- Functions: " + complexCount.get("functions"));
System.out.println("- Arithmetic operators: " + complexCount.get("arithmeticOperators"));
System.out.println("- Special operators: " + complexCount.get("specialOperators"));
System.out.println("- Total operators: " + complexCount.get("total"));
// Example 3: Test approaching the operator limit
System.out.println("\nExample 3: Testing an expression approaching the operator limit");
Map approachingLimit = testOperatorLimit(dynamoDbClient, tableName, key, 290);
System.out.println(approachingLimit.get("message"));
// Example 4: Test exceeding the operator limit
System.out.println("\nExample 4: Testing an expression exceeding the operator limit");
Map exceedingLimit = testOperatorLimit(dynamoDbClient, tableName, key, 310);
System.out.println(exceedingLimit.get("message"));
// Example 5: Breaking down a complex expression
System.out.println("\nExample 5: Breaking down a complex expression into multiple operations");
Map breakdownResult = breakDownComplexExpression(dynamoDbClient, tableName, key, 500);
@SuppressWarnings("unchecked")
Map> results =
(Map>) breakdownResult.get("results");
System.out.println(
"Processed " + results.size() + " of " + breakdownResult.get("totalBatches") + " batches");
// Explain the operator counting rules
System.out.println("\nKey points about DynamoDB expression operator counting:");
System.out.println("1. The maximum number of operators in any expression is 300");
System.out.println("2. Each comparison operator (=, <>, <, <=, >, >=) counts as 1 operator");
System.out.println("3. Each logical operator (AND, OR, NOT) counts as 1 operator");
System.out.println("4. Each function call (attribute_exists, contains, etc.) counts as 1 operator");
System.out.println("5. Each arithmetic operator (+ or -) counts as 1 operator");
System.out.println("6. BETWEEN counts as 2 operators (BETWEEN itself and the AND within it)");
System.out.println("7. IN counts as 1 operator regardless of the number of values");
System.out.println("8. Parentheses for grouping and attribute paths don't count as operators");
System.out.println("9. When you exceed the limit, the error always reports '301 operators'");
System.out.println("10. For complex operations, break them into multiple smaller operations");
} catch (Exception e) {
System.err.println("Error: " + e.getMessage());
e.printStackTrace();
}
}
```
+ For API details, see [UpdateItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/UpdateItem) in *AWS SDK for Java 2.x API Reference*.
### Create a serverless application to manage photos
The following code example shows how to create a serverless application that lets users manage photos using labels.
**SDK for Java 2.x**
Shows how to develop a photo asset management application that detects labels in images using Amazon Rekognition and stores them for later retrieval.
For complete source code and instructions on how to set up and run, see the full example on [ GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/usecases/pam_source_files).
For a deep dive into the origin of this example see the post on [AWS Community](https://community.aws/posts/cloud-journeys/01-serverless-image-recognition-app).
**Services used in this example**
+ API Gateway
+ DynamoDB
+ Lambda
+ Amazon Rekognition
+ Amazon S3
+ Amazon SNS
### Create a table with global secondary index
The following code example shows how to create a table with global secondary index.
**SDK for Java 2.x**
Create DynamoDB table with Global Secondary Index using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.auth.credentials.DefaultCredentialsProvider;
import software.amazon.awssdk.core.waiters.WaiterResponse;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeDefinition;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.CreateTableRequest;
import software.amazon.awssdk.services.dynamodb.model.DeleteTableRequest;
import software.amazon.awssdk.services.dynamodb.model.DescribeTableRequest;
import software.amazon.awssdk.services.dynamodb.model.DescribeTableResponse;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.GlobalSecondaryIndex;
import software.amazon.awssdk.services.dynamodb.model.KeySchemaElement;
import software.amazon.awssdk.services.dynamodb.model.KeyType;
import software.amazon.awssdk.services.dynamodb.model.Projection;
import software.amazon.awssdk.services.dynamodb.model.ProjectionType;
import software.amazon.awssdk.services.dynamodb.model.ProvisionedThroughput;
import software.amazon.awssdk.services.dynamodb.model.PutItemRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import software.amazon.awssdk.services.dynamodb.model.ScalarAttributeType;
import software.amazon.awssdk.services.dynamodb.waiters.DynamoDbWaiter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public void createTable() {
try {
// Attribute definitions
final List attributeDefinitions = new ArrayList<>();
attributeDefinitions.add(AttributeDefinition.builder()
.attributeName(ISSUE_ID_ATTR)
.attributeType(ScalarAttributeType.S)
.build());
attributeDefinitions.add(AttributeDefinition.builder()
.attributeName(TITLE_ATTR)
.attributeType(ScalarAttributeType.S)
.build());
attributeDefinitions.add(AttributeDefinition.builder()
.attributeName(CREATE_DATE_ATTR)
.attributeType(ScalarAttributeType.S)
.build());
attributeDefinitions.add(AttributeDefinition.builder()
.attributeName(DUE_DATE_ATTR)
.attributeType(ScalarAttributeType.S)
.build());
// Key schema for table
final List tableKeySchema = new ArrayList<>();
tableKeySchema.add(KeySchemaElement.builder()
.attributeName(ISSUE_ID_ATTR)
.keyType(KeyType.HASH)
.build()); // Partition key
tableKeySchema.add(KeySchemaElement.builder()
.attributeName(TITLE_ATTR)
.keyType(KeyType.RANGE)
.build()); // Sort key
// Initial provisioned throughput settings for the indexes
final ProvisionedThroughput ptIndex = ProvisionedThroughput.builder()
.readCapacityUnits(1L)
.writeCapacityUnits(1L)
.build();
// CreateDateIndex
final List createDateKeySchema = new ArrayList<>();
createDateKeySchema.add(KeySchemaElement.builder()
.attributeName(CREATE_DATE_ATTR)
.keyType(KeyType.HASH)
.build());
createDateKeySchema.add(KeySchemaElement.builder()
.attributeName(ISSUE_ID_ATTR)
.keyType(KeyType.RANGE)
.build());
final Projection createDateProjection = Projection.builder()
.projectionType(ProjectionType.INCLUDE)
.nonKeyAttributes(DESCRIPTION_ATTR, STATUS_ATTR)
.build();
final GlobalSecondaryIndex createDateIndex = GlobalSecondaryIndex.builder()
.indexName(CREATE_DATE_INDEX)
.keySchema(createDateKeySchema)
.projection(createDateProjection)
.provisionedThroughput(ptIndex)
.build();
// TitleIndex
final List titleKeySchema = new ArrayList<>();
titleKeySchema.add(KeySchemaElement.builder()
.attributeName(TITLE_ATTR)
.keyType(KeyType.HASH)
.build());
titleKeySchema.add(KeySchemaElement.builder()
.attributeName(ISSUE_ID_ATTR)
.keyType(KeyType.RANGE)
.build());
final Projection titleProjection =
Projection.builder().projectionType(ProjectionType.KEYS_ONLY).build();
final GlobalSecondaryIndex titleIndex = GlobalSecondaryIndex.builder()
.indexName(TITLE_INDEX)
.keySchema(titleKeySchema)
.projection(titleProjection)
.provisionedThroughput(ptIndex)
.build();
// DueDateIndex
final List dueDateKeySchema = new ArrayList<>();
dueDateKeySchema.add(KeySchemaElement.builder()
.attributeName(DUE_DATE_ATTR)
.keyType(KeyType.HASH)
.build());
final Projection dueDateProjection =
Projection.builder().projectionType(ProjectionType.ALL).build();
final GlobalSecondaryIndex dueDateIndex = GlobalSecondaryIndex.builder()
.indexName(DUE_DATE_INDEX)
.keySchema(dueDateKeySchema)
.projection(dueDateProjection)
.provisionedThroughput(ptIndex)
.build();
final CreateTableRequest createTableRequest = CreateTableRequest.builder()
.tableName(TABLE_NAME)
.keySchema(tableKeySchema)
.attributeDefinitions(attributeDefinitions)
.globalSecondaryIndexes(createDateIndex, titleIndex, dueDateIndex)
.provisionedThroughput(ProvisionedThroughput.builder()
.readCapacityUnits(1L)
.writeCapacityUnits(1L)
.build())
.build();
System.out.println("Creating table " + TABLE_NAME + "...");
dynamoDbClient.createTable(createTableRequest);
// Wait for table to become active
System.out.println("Waiting for " + TABLE_NAME + " to become ACTIVE...");
final DynamoDbWaiter waiter = dynamoDbClient.waiter();
final DescribeTableRequest describeTableRequest =
DescribeTableRequest.builder().tableName(TABLE_NAME).build();
final WaiterResponse waiterResponse =
waiter.waitUntilTableExists(describeTableRequest);
waiterResponse.matched().response().ifPresent(response -> System.out.println("Table is now ready for use"));
} catch (DynamoDbException e) {
System.err.println("Error creating table: " + e.getMessage());
e.printStackTrace();
}
}
```
+ For API details, see [CreateTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/CreateTable) in *AWS SDK for Java 2.x API Reference*.
### Create a table with warm throughput enabled
The following code example shows how to create a table with warm throughput enabled.
**SDK for Java 2.x**
Create DynamoDB table with warm throughput setting using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeDefinition;
import software.amazon.awssdk.services.dynamodb.model.CreateTableRequest;
import software.amazon.awssdk.services.dynamodb.model.CreateTableResponse;
import software.amazon.awssdk.services.dynamodb.model.GlobalSecondaryIndex;
import software.amazon.awssdk.services.dynamodb.model.KeySchemaElement;
import software.amazon.awssdk.services.dynamodb.model.KeyType;
import software.amazon.awssdk.services.dynamodb.model.Projection;
import software.amazon.awssdk.services.dynamodb.model.ProvisionedThroughput;
import software.amazon.awssdk.services.dynamodb.model.ScalarAttributeType;
import software.amazon.awssdk.services.dynamodb.model.WarmThroughput;
public static WarmThroughput buildWarmThroughput(final Long readUnitsPerSecond, final Long writeUnitsPerSecond) {
return WarmThroughput.builder()
.readUnitsPerSecond(readUnitsPerSecond)
.writeUnitsPerSecond(writeUnitsPerSecond)
.build();
}
/**
* Builds a ProvisionedThroughput object with the specified read and write capacity units.
*
* @param readCapacityUnits The read capacity units
* @param writeCapacityUnits The write capacity units
* @return A configured ProvisionedThroughput object
*/
public static ProvisionedThroughput buildProvisionedThroughput(
final Long readCapacityUnits, final Long writeCapacityUnits) {
return ProvisionedThroughput.builder()
.readCapacityUnits(readCapacityUnits)
.writeCapacityUnits(writeCapacityUnits)
.build();
}
/**
* Builds an AttributeDefinition with the specified name and type.
*
* @param attributeName The attribute name
* @param scalarAttributeType The attribute type
* @return A configured AttributeDefinition
*/
private static AttributeDefinition buildAttributeDefinition(
final String attributeName, final ScalarAttributeType scalarAttributeType) {
return AttributeDefinition.builder()
.attributeName(attributeName)
.attributeType(scalarAttributeType)
.build();
}
/**
* Builds a KeySchemaElement with the specified name and key type.
*
* @param attributeName The attribute name
* @param keyType The key type (HASH or RANGE)
* @return A configured KeySchemaElement
*/
private static KeySchemaElement buildKeySchemaElement(final String attributeName, final KeyType keyType) {
return KeySchemaElement.builder()
.attributeName(attributeName)
.keyType(keyType)
.build();
}
/**
* Creates a DynamoDB table with the specified configuration including warm throughput settings.
*
* @param ddb The DynamoDB client
* @param tableName The name of the table to create
* @param partitionKey The partition key attribute name
* @param sortKey The sort key attribute name
* @param miscellaneousKeyAttribute Additional key attribute name for GSI
* @param nonKeyAttribute Non-key attribute to include in GSI projection
* @param tableReadCapacityUnits Read capacity units for the table
* @param tableWriteCapacityUnits Write capacity units for the table
* @param tableWarmReadUnitsPerSecond Warm read units per second for the table
* @param tableWarmWriteUnitsPerSecond Warm write units per second for the table
* @param globalSecondaryIndexName The name of the GSI to create
* @param globalSecondaryIndexReadCapacityUnits Read capacity units for the GSI
* @param globalSecondaryIndexWriteCapacityUnits Write capacity units for the GSI
* @param globalSecondaryIndexWarmReadUnitsPerSecond Warm read units per second for the GSI
* @param globalSecondaryIndexWarmWriteUnitsPerSecond Warm write units per second for the GSI
*/
public static void createDynamoDBTable(
final DynamoDbClient ddb,
final String tableName,
final String partitionKey,
final String sortKey,
final String miscellaneousKeyAttribute,
final String nonKeyAttribute,
final Long tableReadCapacityUnits,
final Long tableWriteCapacityUnits,
final Long tableWarmReadUnitsPerSecond,
final Long tableWarmWriteUnitsPerSecond,
final String globalSecondaryIndexName,
final Long globalSecondaryIndexReadCapacityUnits,
final Long globalSecondaryIndexWriteCapacityUnits,
final Long globalSecondaryIndexWarmReadUnitsPerSecond,
final Long globalSecondaryIndexWarmWriteUnitsPerSecond) {
// Define the table attributes
final AttributeDefinition partitionKeyAttribute = buildAttributeDefinition(partitionKey, ScalarAttributeType.S);
final AttributeDefinition sortKeyAttribute = buildAttributeDefinition(sortKey, ScalarAttributeType.S);
final AttributeDefinition miscellaneousKeyAttributeDefinition =
buildAttributeDefinition(miscellaneousKeyAttribute, ScalarAttributeType.N);
final AttributeDefinition[] attributeDefinitions = {
partitionKeyAttribute, sortKeyAttribute, miscellaneousKeyAttributeDefinition
};
// Define the table key schema
final KeySchemaElement partitionKeyElement = buildKeySchemaElement(partitionKey, KeyType.HASH);
final KeySchemaElement sortKeyElement = buildKeySchemaElement(sortKey, KeyType.RANGE);
final KeySchemaElement[] keySchema = {partitionKeyElement, sortKeyElement};
// Define the provisioned throughput for the table
final ProvisionedThroughput provisionedThroughput =
buildProvisionedThroughput(tableReadCapacityUnits, tableWriteCapacityUnits);
// Define the Global Secondary Index (GSI)
final KeySchemaElement globalSecondaryIndexPartitionKeyElement = buildKeySchemaElement(sortKey, KeyType.HASH);
final KeySchemaElement globalSecondaryIndexSortKeyElement =
buildKeySchemaElement(miscellaneousKeyAttribute, KeyType.RANGE);
final KeySchemaElement[] gsiKeySchema = {
globalSecondaryIndexPartitionKeyElement, globalSecondaryIndexSortKeyElement
};
final Projection gsiProjection = Projection.builder()
.projectionType(PROJECTION_TYPE_INCLUDE)
.nonKeyAttributes(nonKeyAttribute)
.build();
final ProvisionedThroughput gsiProvisionedThroughput =
buildProvisionedThroughput(globalSecondaryIndexReadCapacityUnits, globalSecondaryIndexWriteCapacityUnits);
// Define the warm throughput for the Global Secondary Index (GSI)
final WarmThroughput gsiWarmThroughput = buildWarmThroughput(
globalSecondaryIndexWarmReadUnitsPerSecond, globalSecondaryIndexWarmWriteUnitsPerSecond);
final GlobalSecondaryIndex globalSecondaryIndex = GlobalSecondaryIndex.builder()
.indexName(globalSecondaryIndexName)
.keySchema(gsiKeySchema)
.projection(gsiProjection)
.provisionedThroughput(gsiProvisionedThroughput)
.warmThroughput(gsiWarmThroughput)
.build();
// Define the warm throughput for the table
final WarmThroughput tableWarmThroughput =
buildWarmThroughput(tableWarmReadUnitsPerSecond, tableWarmWriteUnitsPerSecond);
final CreateTableRequest request = CreateTableRequest.builder()
.tableName(tableName)
.attributeDefinitions(attributeDefinitions)
.keySchema(keySchema)
.provisionedThroughput(provisionedThroughput)
.globalSecondaryIndexes(globalSecondaryIndex)
.warmThroughput(tableWarmThroughput)
.build();
final CreateTableResponse response = ddb.createTable(request);
System.out.println(response);
}
```
+ For API details, see [CreateTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/CreateTable) in *AWS SDK for Java 2.x API Reference*.
### Create a web application to track DynamoDB data
The following code example shows how to create a web application that tracks work items in an Amazon DynamoDB table and uses Amazon Simple Email Service (Amazon SES) to send reports.
**SDK for Java 2.x**
Shows how to use the Amazon DynamoDB API to create a dynamic web application that tracks DynamoDB work data.
For complete source code and instructions on how to set up and run, see the full example on [GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/usecases/creating_dynamodb_web_app).
**Services used in this example**
+ DynamoDB
+ Amazon SES
### Create an item with a TTL
The following code example shows how to create an item with TTL.
**SDK for Java 2.x**
```
package com.amazon.samplelib.ttl;
import com.amazon.samplelib.CodeSampleUtils;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.PutItemRequest;
import software.amazon.awssdk.services.dynamodb.model.PutItemResponse;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import java.util.HashMap;
import java.util.Map;
import java.util.Optional;
/**
* Creates an item in a DynamoDB table with TTL attributes.
* This class demonstrates how to add TTL expiration timestamps to DynamoDB items.
*/
public class CreateTTL {
private static final String USAGE =
"""
Usage:
Where:
tableName - The Amazon DynamoDB table being queried.
primaryKey - The name of the primary key. Also known as the hash or partition key.
sortKey - The name of the sort key. Also known as the range attribute.
region (optional) - The AWS region that the Amazon DynamoDB table is located in. (Default: us-east-1)
""";
private static final int DAYS_TO_EXPIRE = 90;
private static final int SECONDS_PER_DAY = 24 * 60 * 60;
private static final String PRIMARY_KEY_ATTR = "primaryKey";
private static final String SORT_KEY_ATTR = "sortKey";
private static final String CREATION_DATE_ATTR = "creationDate";
private static final String EXPIRE_AT_ATTR = "expireAt";
private static final String SUCCESS_MESSAGE = "%s PutItem operation with TTL successful.";
private static final String TABLE_NOT_FOUND_ERROR = "Error: The Amazon DynamoDB table \"%s\" can't be found.";
private final DynamoDbClient dynamoDbClient;
/**
* Constructs a CreateTTL instance with the specified DynamoDB client.
*
* @param dynamoDbClient The DynamoDB client to use
*/
public CreateTTL(final DynamoDbClient dynamoDbClient) {
this.dynamoDbClient = dynamoDbClient;
}
/**
* Constructs a CreateTTL with a default DynamoDB client.
*/
public CreateTTL() {
this.dynamoDbClient = null;
}
/**
* Main method to demonstrate creating an item with TTL.
*
* @param args Command line arguments
*/
public static void main(final String[] args) {
try {
int result = new CreateTTL().processArgs(args);
System.exit(result);
} catch (Exception e) {
System.err.println(e.getMessage());
System.exit(1);
}
}
/**
* Process command line arguments and create an item with TTL.
*
* @param args Command line arguments
* @return 0 if successful, non-zero otherwise
* @throws ResourceNotFoundException If the table doesn't exist
* @throws DynamoDbException If an error occurs during the operation
* @throws IllegalArgumentException If arguments are invalid
*/
public int processArgs(final String[] args) {
// Argument validation (remove or replace this line when reusing this code)
CodeSampleUtils.validateArgs(args, new int[] {3, 4}, USAGE);
final String tableName = args[0];
final String primaryKey = args[1];
final String sortKey = args[2];
final Region region = Optional.ofNullable(args.length > 3 ? args[3] : null)
.map(Region::of)
.orElse(Region.US_EAST_1);
try (DynamoDbClient ddb = dynamoDbClient != null
? dynamoDbClient
: DynamoDbClient.builder().region(region).build()) {
final CreateTTL createTTL = new CreateTTL(ddb);
createTTL.createItemWithTTL(tableName, primaryKey, sortKey);
return 0;
} catch (Exception e) {
throw e;
}
}
/**
* Creates an item in the specified table with TTL attributes.
*
* @param tableName The name of the table
* @param primaryKeyValue The value for the primary key
* @param sortKeyValue The value for the sort key
* @return The response from the PutItem operation
* @throws ResourceNotFoundException If the table doesn't exist
* @throws DynamoDbException If an error occurs during the operation
*/
public PutItemResponse createItemWithTTL(
final String tableName, final String primaryKeyValue, final String sortKeyValue) {
// Get current time in epoch second format
final long createDate = System.currentTimeMillis() / 1000;
// Calculate expiration time 90 days from now in epoch second format
final long expireDate = createDate + (DAYS_TO_EXPIRE * SECONDS_PER_DAY);
final Map itemMap = new HashMap<>();
itemMap.put(
PRIMARY_KEY_ATTR, AttributeValue.builder().s(primaryKeyValue).build());
itemMap.put(SORT_KEY_ATTR, AttributeValue.builder().s(sortKeyValue).build());
itemMap.put(
CREATION_DATE_ATTR,
AttributeValue.builder().n(String.valueOf(createDate)).build());
itemMap.put(
EXPIRE_AT_ATTR,
AttributeValue.builder().n(String.valueOf(expireDate)).build());
final PutItemRequest request =
PutItemRequest.builder().tableName(tableName).item(itemMap).build();
try {
final PutItemResponse response = dynamoDbClient.putItem(request);
System.out.println(String.format(SUCCESS_MESSAGE, tableName));
return response;
} catch (ResourceNotFoundException e) {
System.err.format(TABLE_NOT_FOUND_ERROR, tableName);
throw e;
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
throw e;
}
}
}
```
+ For API details, see [PutItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/PutItem) in *AWS SDK for Java 2.x API Reference*.
### Create and manage MRSC global tables
The following code example shows how to create and manage DynamoDB global tables with Multi-Region Strong Consistency (MRSC).
+ Create a table with Multi-Region Strong Consistency.
+ Verify MRSC configuration and replica status.
+ Test strong consistency across Regions with immediate reads.
+ Perform conditional writes with MRSC guarantees.
+ Clean up MRSC global table resources.
**SDK for Java 2.x**
Create a regional table ready for MRSC conversion using AWS SDK for Java 2.x.
```
public static CreateTableResponse createRegionalTable(final DynamoDbClient dynamoDbClient, final String tableName) {
if (dynamoDbClient == null) {
throw new IllegalArgumentException("DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
try {
LOGGER.info("Creating regional table: " + tableName + " (must be empty for MRSC)");
CreateTableRequest createTableRequest = CreateTableRequest.builder()
.tableName(tableName)
.attributeDefinitions(
AttributeDefinition.builder()
.attributeName("Artist")
.attributeType(ScalarAttributeType.S)
.build(),
AttributeDefinition.builder()
.attributeName("SongTitle")
.attributeType(ScalarAttributeType.S)
.build())
.keySchema(
KeySchemaElement.builder()
.attributeName("Artist")
.keyType(KeyType.HASH)
.build(),
KeySchemaElement.builder()
.attributeName("SongTitle")
.keyType(KeyType.RANGE)
.build())
.billingMode(BillingMode.PAY_PER_REQUEST)
.build();
CreateTableResponse response = dynamoDbClient.createTable(createTableRequest);
LOGGER.info("Regional table creation initiated. Status: "
+ response.tableDescription().tableStatus());
return response;
} catch (DynamoDbException e) {
LOGGER.severe("Failed to create regional table: " + tableName + " - " + e.getMessage());
throw DynamoDbException.builder()
.message("Failed to create regional table: " + tableName)
.cause(e)
.build();
}
}
```
Convert a regional table to MRSC with replicas and witness using AWS SDK for Java 2.x.
```
public static UpdateTableResponse convertToMRSCWithWitness(
final DynamoDbClient dynamoDbClient,
final String tableName,
final Region replicaRegion,
final Region witnessRegion) {
if (dynamoDbClient == null) {
throw new IllegalArgumentException("DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
if (replicaRegion == null) {
throw new IllegalArgumentException("Replica region cannot be null");
}
if (witnessRegion == null) {
throw new IllegalArgumentException("Witness region cannot be null");
}
try {
LOGGER.info("Converting table to MRSC with replica in " + replicaRegion.id() + " and witness in "
+ witnessRegion.id());
// Create replica update using ReplicationGroupUpdate
ReplicationGroupUpdate replicaUpdate = ReplicationGroupUpdate.builder()
.create(CreateReplicationGroupMemberAction.builder()
.regionName(replicaRegion.id())
.build())
.build();
// Create witness update
GlobalTableWitnessGroupUpdate witnessUpdate = GlobalTableWitnessGroupUpdate.builder()
.create(CreateGlobalTableWitnessGroupMemberAction.builder()
.regionName(witnessRegion.id())
.build())
.build();
UpdateTableRequest updateTableRequest = UpdateTableRequest.builder()
.tableName(tableName)
.replicaUpdates(List.of(replicaUpdate))
.globalTableWitnessUpdates(List.of(witnessUpdate))
.multiRegionConsistency(MultiRegionConsistency.STRONG)
.build();
UpdateTableResponse response = dynamoDbClient.updateTable(updateTableRequest);
LOGGER.info("MRSC conversion initiated. Status: "
+ response.tableDescription().tableStatus());
LOGGER.info("UpdateTableResponse full object: " + response);
return response;
} catch (DynamoDbException e) {
LOGGER.severe("Failed to convert table to MRSC: " + tableName + " - " + e.getMessage());
throw DynamoDbException.builder()
.message("Failed to convert table to MRSC: " + tableName)
.cause(e)
.build();
}
}
```
Describe an MRSC global table configuration using AWS SDK for Java 2.x.
```
public static DescribeTableResponse describeMRSCTable(final DynamoDbClient dynamoDbClient, final String tableName) {
if (dynamoDbClient == null) {
throw new IllegalArgumentException("DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
try {
LOGGER.info("Describing MRSC global table: " + tableName);
DescribeTableRequest request =
DescribeTableRequest.builder().tableName(tableName).build();
DescribeTableResponse response = dynamoDbClient.describeTable(request);
LOGGER.info("Table status: " + response.table().tableStatus());
LOGGER.info("Multi-region consistency: " + response.table().multiRegionConsistency());
if (response.table().replicas() != null
&& !response.table().replicas().isEmpty()) {
LOGGER.info("Number of replicas: " + response.table().replicas().size());
response.table()
.replicas()
.forEach(replica -> LOGGER.info(
"Replica region: " + replica.regionName() + ", Status: " + replica.replicaStatus()));
}
if (response.table().globalTableWitnesses() != null
&& !response.table().globalTableWitnesses().isEmpty()) {
LOGGER.info("Number of witnesses: "
+ response.table().globalTableWitnesses().size());
response.table()
.globalTableWitnesses()
.forEach(witness -> LOGGER.info(
"Witness region: " + witness.regionName() + ", Status: " + witness.witnessStatus()));
}
return response;
} catch (ResourceNotFoundException e) {
LOGGER.severe("Table not found: " + tableName + " - " + e.getMessage());
throw DynamoDbException.builder()
.message("Table not found: " + tableName)
.cause(e)
.build();
} catch (DynamoDbException e) {
LOGGER.severe("Failed to describe table: " + tableName + " - " + e.getMessage());
throw DynamoDbException.builder()
.message("Failed to describe table: " + tableName)
.cause(e)
.build();
}
}
```
Add test items to verify MRSC strong consistency using AWS SDK for Java 2.x.
```
public static PutItemResponse putTestItem(
final DynamoDbClient dynamoDbClient,
final String tableName,
final String artist,
final String songTitle,
final String album,
final String year) {
if (dynamoDbClient == null) {
throw new IllegalArgumentException("DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
if (artist == null || artist.trim().isEmpty()) {
throw new IllegalArgumentException("Artist cannot be null or empty");
}
if (songTitle == null || songTitle.trim().isEmpty()) {
throw new IllegalArgumentException("Song title cannot be null or empty");
}
try {
LOGGER.info("Adding test item to MRSC global table: " + tableName);
Map item = new HashMap<>();
item.put("Artist", AttributeValue.builder().s(artist).build());
item.put("SongTitle", AttributeValue.builder().s(songTitle).build());
if (album != null && !album.trim().isEmpty()) {
item.put("Album", AttributeValue.builder().s(album).build());
}
if (year != null && !year.trim().isEmpty()) {
item.put("Year", AttributeValue.builder().n(year).build());
}
PutItemRequest putItemRequest =
PutItemRequest.builder().tableName(tableName).item(item).build();
PutItemResponse response = dynamoDbClient.putItem(putItemRequest);
LOGGER.info("Test item added successfully with strong consistency");
return response;
} catch (DynamoDbException e) {
LOGGER.severe("Failed to add test item to table: " + tableName + " - " + e.getMessage());
throw DynamoDbException.builder()
.message("Failed to add test item to table: " + tableName)
.cause(e)
.build();
}
}
```
Read items with consistent reads from MRSC replicas using AWS SDK for Java 2.x.
```
public static GetItemResponse getItemWithConsistentRead(
final DynamoDbClient dynamoDbClient, final String tableName, final String artist, final String songTitle) {
if (dynamoDbClient == null) {
throw new IllegalArgumentException("DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
if (artist == null || artist.trim().isEmpty()) {
throw new IllegalArgumentException("Artist cannot be null or empty");
}
if (songTitle == null || songTitle.trim().isEmpty()) {
throw new IllegalArgumentException("Song title cannot be null or empty");
}
try {
LOGGER.info("Reading item from MRSC global table with consistent read: " + tableName);
Map key = new HashMap<>();
key.put("Artist", AttributeValue.builder().s(artist).build());
key.put("SongTitle", AttributeValue.builder().s(songTitle).build());
GetItemRequest getItemRequest = GetItemRequest.builder()
.tableName(tableName)
.key(key)
.consistentRead(true)
.build();
GetItemResponse response = dynamoDbClient.getItem(getItemRequest);
if (response.hasItem()) {
LOGGER.info("Item found with strong consistency - no wait time needed");
} else {
LOGGER.info("Item not found");
}
return response;
} catch (DynamoDbException e) {
LOGGER.severe("Failed to read item from table: " + tableName + " - " + e.getMessage());
throw DynamoDbException.builder()
.message("Failed to read item from table: " + tableName)
.cause(e)
.build();
}
}
```
Perform conditional updates with MRSC guarantees using AWS SDK for Java 2.x.
```
public static UpdateItemResponse performConditionalUpdate(
final DynamoDbClient dynamoDbClient,
final String tableName,
final String artist,
final String songTitle,
final String rating) {
if (dynamoDbClient == null) {
throw new IllegalArgumentException("DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
if (artist == null || artist.trim().isEmpty()) {
throw new IllegalArgumentException("Artist cannot be null or empty");
}
if (songTitle == null || songTitle.trim().isEmpty()) {
throw new IllegalArgumentException("Song title cannot be null or empty");
}
if (rating == null || rating.trim().isEmpty()) {
throw new IllegalArgumentException("Rating cannot be null or empty");
}
try {
LOGGER.info("Performing conditional update on MRSC global table: " + tableName);
Map key = new HashMap<>();
key.put("Artist", AttributeValue.builder().s(artist).build());
key.put("SongTitle", AttributeValue.builder().s(songTitle).build());
Map expressionAttributeNames = new HashMap<>();
expressionAttributeNames.put("#rating", "Rating");
Map expressionAttributeValues = new HashMap<>();
expressionAttributeValues.put(
":rating", AttributeValue.builder().n(rating).build());
UpdateItemRequest updateItemRequest = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("SET #rating = :rating")
.conditionExpression("attribute_exists(Artist)")
.expressionAttributeNames(expressionAttributeNames)
.expressionAttributeValues(expressionAttributeValues)
.build();
UpdateItemResponse response = dynamoDbClient.updateItem(updateItemRequest);
LOGGER.info("Conditional update successful - demonstrates strong consistency");
return response;
} catch (ConditionalCheckFailedException e) {
LOGGER.warning("Conditional check failed: " + e.getMessage());
throw e;
} catch (DynamoDbException e) {
LOGGER.severe("Failed to perform conditional update: " + tableName + " - " + e.getMessage());
throw DynamoDbException.builder()
.message("Failed to perform conditional update: " + tableName)
.cause(e)
.build();
}
}
```
Wait for MRSC replicas and witnesses to become active using AWS SDK for Java 2.x.
```
public static void waitForMRSCReplicasActive(
final DynamoDbClient dynamoDbClient, final String tableName, final int maxWaitTimeSeconds)
throws InterruptedException {
if (dynamoDbClient == null) {
throw new IllegalArgumentException("DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
if (maxWaitTimeSeconds <= 0) {
throw new IllegalArgumentException("Max wait time must be positive");
}
try {
LOGGER.info("Waiting for MRSC replicas and witnesses to become active: " + tableName);
final long startTime = System.currentTimeMillis();
final long maxWaitTimeMillis = maxWaitTimeSeconds * 1000L;
int backoffSeconds = 5; // Start with 5 second intervals
final int maxBackoffSeconds = 30; // Cap at 30 seconds
while (System.currentTimeMillis() - startTime < maxWaitTimeMillis) {
DescribeTableResponse response = describeMRSCTable(dynamoDbClient, tableName);
boolean allActive = true;
StringBuilder statusReport = new StringBuilder();
if (response.table().multiRegionConsistency() == null
|| !MultiRegionConsistency.STRONG
.toString()
.equals(response.table().multiRegionConsistency().toString())) {
allActive = false;
statusReport
.append("MultiRegionConsistency: ")
.append(response.table().multiRegionConsistency())
.append(" ");
}
if (response.table().replicas() == null
|| response.table().replicas().isEmpty()) {
allActive = false;
statusReport.append("No replicas found. ");
}
if (response.table().globalTableWitnesses() == null
|| response.table().globalTableWitnesses().isEmpty()) {
allActive = false;
statusReport.append("No witnesses found. ");
}
// Check table status
if (!"ACTIVE".equals(response.table().tableStatus().toString())) {
allActive = false;
statusReport
.append("Table: ")
.append(response.table().tableStatus())
.append(" ");
}
// Check replica status
if (response.table().replicas() != null) {
for (var replica : response.table().replicas()) {
if (!"ACTIVE".equals(replica.replicaStatus().toString())) {
allActive = false;
statusReport
.append("Replica(")
.append(replica.regionName())
.append("): ")
.append(replica.replicaStatus())
.append(" ");
}
}
}
// Check witness status
if (response.table().globalTableWitnesses() != null) {
for (var witness : response.table().globalTableWitnesses()) {
if (!"ACTIVE".equals(witness.witnessStatus().toString())) {
allActive = false;
statusReport
.append("Witness(")
.append(witness.regionName())
.append("): ")
.append(witness.witnessStatus())
.append(" ");
}
}
}
if (allActive) {
LOGGER.info("All MRSC replicas and witnesses are now active: " + tableName);
return;
}
LOGGER.info("Waiting for MRSC components to become active. Status: " + statusReport.toString());
LOGGER.info("Next check in " + backoffSeconds + " seconds...");
tempWait(backoffSeconds);
// Exponential backoff with cap
backoffSeconds = Math.min(backoffSeconds * 2, maxBackoffSeconds);
}
throw DynamoDbException.builder()
.message("Timeout waiting for MRSC replicas to become active after " + maxWaitTimeSeconds + " seconds")
.build();
} catch (DynamoDbException | InterruptedException e) {
LOGGER.severe("Failed to wait for MRSC replicas to become active: " + tableName + " - " + e.getMessage());
throw e;
}
}
```
Clean up MRSC replicas and witnesses using AWS SDK for Java 2.x.
```
public static UpdateTableResponse cleanupMRSCReplicas(
final DynamoDbClient dynamoDbClient,
final String tableName,
final Region replicaRegion,
final Region witnessRegion) {
if (dynamoDbClient == null) {
throw new IllegalArgumentException("DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
if (replicaRegion == null) {
throw new IllegalArgumentException("Replica region cannot be null");
}
if (witnessRegion == null) {
throw new IllegalArgumentException("Witness region cannot be null");
}
try {
LOGGER.info("Cleaning up MRSC replicas and witnesses for table: " + tableName);
// Remove replica using ReplicationGroupUpdate
ReplicationGroupUpdate replicaUpdate = ReplicationGroupUpdate.builder()
.delete(DeleteReplicationGroupMemberAction.builder()
.regionName(replicaRegion.id())
.build())
.build();
// Remove witness
GlobalTableWitnessGroupUpdate witnessUpdate = GlobalTableWitnessGroupUpdate.builder()
.delete(DeleteGlobalTableWitnessGroupMemberAction.builder()
.regionName(witnessRegion.id())
.build())
.build();
UpdateTableRequest updateTableRequest = UpdateTableRequest.builder()
.tableName(tableName)
.replicaUpdates(List.of(replicaUpdate))
.globalTableWitnessUpdates(List.of(witnessUpdate))
.build();
UpdateTableResponse response = dynamoDbClient.updateTable(updateTableRequest);
LOGGER.info("MRSC cleanup initiated - removing replica and witness. Response: " + response);
return response;
} catch (DynamoDbException e) {
LOGGER.severe("Failed to cleanup MRSC replicas: " + tableName + " - " + e.getMessage());
throw DynamoDbException.builder()
.message("Failed to cleanup MRSC replicas: " + tableName)
.cause(e)
.build();
}
}
```
Complete MRSC workflow demonstration using AWS SDK for Java 2.x.
```
public static void demonstrateCompleteMRSCWorkflow(
final DynamoDbClient primaryClient,
final DynamoDbClient replicaClient,
final String tableName,
final Region replicaRegion,
final Region witnessRegion)
throws InterruptedException {
if (primaryClient == null) {
throw new IllegalArgumentException("Primary DynamoDB client cannot be null");
}
if (replicaClient == null) {
throw new IllegalArgumentException("Replica DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
if (replicaRegion == null) {
throw new IllegalArgumentException("Replica region cannot be null");
}
if (witnessRegion == null) {
throw new IllegalArgumentException("Witness region cannot be null");
}
try {
LOGGER.info("=== Starting Complete MRSC Workflow Demonstration ===");
// Step 1: Create an empty single-Region table
LOGGER.info("Step 1: Creating empty single-Region table");
createRegionalTable(primaryClient, tableName);
// Use the existing GlobalTableOperations method for basic table waiting
LOGGER.info("Intermediate step: Waiting for table [" + tableName + "] to become active before continuing");
GlobalTableOperations.waitForTableActive(primaryClient, tableName);
// Step 2: Convert to MRSC with replica and witness
LOGGER.info("Step 2: Converting to MRSC with replica and witness");
convertToMRSCWithWitness(primaryClient, tableName, replicaRegion, witnessRegion);
// Wait for MRSC conversion to complete using MRSC-specific waiter
LOGGER.info("Waiting for MRSC conversion to complete...");
waitForMRSCReplicasActive(primaryClient, tableName);
LOGGER.info("Intermediate step: Waiting for table [" + tableName + "] to become active before continuing");
GlobalTableOperations.waitForTableActive(primaryClient, tableName);
// Step 3: Verify MRSC configuration
LOGGER.info("Step 3: Verifying MRSC configuration");
describeMRSCTable(primaryClient, tableName);
// Step 4: Test strong consistency with data operations
LOGGER.info("Step 4: Testing strong consistency with data operations");
// Add test item to primary region
putTestItem(primaryClient, tableName, "The Beatles", "Hey Jude", "The Beatles 1967-1970", "1968");
// Immediately read from replica region (no wait needed with MRSC)
LOGGER.info("Reading from replica region immediately (strong consistency):");
GetItemResponse getResponse =
getItemWithConsistentRead(replicaClient, tableName, "The Beatles", "Hey Jude");
if (getResponse.hasItem()) {
LOGGER.info("✓ Strong consistency verified - item immediately available in replica region");
} else {
LOGGER.warning("✗ Item not found in replica region");
}
// Test conditional update from replica region
LOGGER.info("Testing conditional update from replica region:");
performConditionalUpdate(replicaClient, tableName, "The Beatles", "Hey Jude", "5");
LOGGER.info("✓ Conditional update successful - demonstrates strong consistency");
// Step 5: Cleanup
LOGGER.info("Step 5: Cleaning up resources");
cleanupMRSCReplicas(primaryClient, tableName, replicaRegion, witnessRegion);
// Wait for cleanup to complete using basic table waiter
LOGGER.info("Waiting for replica cleanup to complete...");
GlobalTableOperations.waitForTableActive(primaryClient, tableName);
// "Halt" until replica/witness cleanup is complete
DescribeTableResponse cleanupVerification = describeMRSCTable(primaryClient, tableName);
int backoffSeconds = 5; // Start with 5 second intervals
while (cleanupVerification.table().multiRegionConsistency() != null) {
LOGGER.info("Waiting additional time (" + backoffSeconds + " seconds) for MRSC cleanup to complete...");
tempWait(backoffSeconds);
// Exponential backoff with cap
backoffSeconds = Math.min(backoffSeconds * 2, 30);
cleanupVerification = describeMRSCTable(primaryClient, tableName);
}
// Delete the primary table
deleteTable(primaryClient, tableName);
LOGGER.info("=== MRSC Workflow Demonstration Complete ===");
LOGGER.info("");
LOGGER.info("Key benefits of Multi-Region Strong Consistency (MRSC):");
LOGGER.info("- Immediate consistency across all regions (no eventual consistency delays)");
LOGGER.info("- Simplified application logic (no need to handle eventual consistency)");
LOGGER.info("- Support for conditional writes and transactions across regions");
LOGGER.info("- Consistent read operations from any region without waiting");
} catch (DynamoDbException | InterruptedException e) {
LOGGER.severe("MRSC workflow failed: " + e.getMessage());
throw e;
}
}
```
+ For API details, see the following topics in *AWS SDK for Java 2.x API Reference*.
+ [CreateTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/CreateTable)
+ [DeleteTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/DeleteTable)
+ [DescribeTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/DescribeTable)
+ [GetItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/GetItem)
+ [PutItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/PutItem)
+ [UpdateItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/UpdateItem)
+ [UpdateTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/UpdateTable)
### Create and manage global tables demonstrating MREC
The following code example shows how to create and manage DynamoDB global tables with replicas across multiple Regions.
+ Create a table with Global Secondary Index and DynamoDB Streams.
+ Add replicas in different Regions to create a global table.
+ Remove replicas from a global table.
+ Add test items to verify replication across Regions.
+ Describe global table configuration and replica status.
**SDK for Java 2.x**
Create a table with Global Secondary Index and DynamoDB Streams using AWS SDK for Java 2.x.
```
public static CreateTableResponse createTableWithGSI(
final DynamoDbClient dynamoDbClient, final String tableName, final String indexName) {
if (dynamoDbClient == null) {
throw new IllegalArgumentException("DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
if (indexName == null || indexName.trim().isEmpty()) {
throw new IllegalArgumentException("Index name cannot be null or empty");
}
try {
LOGGER.info("Creating table: " + tableName + " with GSI: " + indexName);
CreateTableRequest createTableRequest = CreateTableRequest.builder()
.tableName(tableName)
.attributeDefinitions(
AttributeDefinition.builder()
.attributeName("Artist")
.attributeType(ScalarAttributeType.S)
.build(),
AttributeDefinition.builder()
.attributeName("SongTitle")
.attributeType(ScalarAttributeType.S)
.build())
.keySchema(
KeySchemaElement.builder()
.attributeName("Artist")
.keyType(KeyType.HASH)
.build(),
KeySchemaElement.builder()
.attributeName("SongTitle")
.keyType(KeyType.RANGE)
.build())
.billingMode(BillingMode.PAY_PER_REQUEST)
.globalSecondaryIndexes(GlobalSecondaryIndex.builder()
.indexName(indexName)
.keySchema(KeySchemaElement.builder()
.attributeName("SongTitle")
.keyType(KeyType.HASH)
.build())
.projection(
Projection.builder().projectionType(ProjectionType.ALL).build())
.build())
.streamSpecification(StreamSpecification.builder()
.streamEnabled(true)
.streamViewType(StreamViewType.NEW_AND_OLD_IMAGES)
.build())
.build();
CreateTableResponse response = dynamoDbClient.createTable(createTableRequest);
LOGGER.info("Table creation initiated. Status: "
+ response.tableDescription().tableStatus());
return response;
} catch (DynamoDbException e) {
LOGGER.severe("Failed to create table: " + tableName + " - " + e.getMessage());
throw e;
}
}
```
Wait for a table to become active using AWS SDK for Java 2.x.
```
public static void waitForTableActive(final DynamoDbClient dynamoDbClient, final String tableName) {
if (dynamoDbClient == null) {
throw new IllegalArgumentException("DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
try {
LOGGER.info("Waiting for table to become active: " + tableName);
try (DynamoDbWaiter waiter =
DynamoDbWaiter.builder().client(dynamoDbClient).build()) {
DescribeTableRequest request =
DescribeTableRequest.builder().tableName(tableName).build();
waiter.waitUntilTableExists(request);
LOGGER.info("Table is now active: " + tableName);
}
} catch (DynamoDbException e) {
LOGGER.severe("Failed to wait for table to become active: " + tableName + " - " + e.getMessage());
throw e;
}
}
```
Add a replica to create or extend a global table using AWS SDK for Java 2.x.
```
public static UpdateTableResponse addReplica(
final DynamoDbClient dynamoDbClient,
final String tableName,
final Region replicaRegion,
final String indexName,
final Long readCapacity) {
if (dynamoDbClient == null) {
throw new IllegalArgumentException("DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
if (replicaRegion == null) {
throw new IllegalArgumentException("Replica region cannot be null");
}
if (indexName == null || indexName.trim().isEmpty()) {
throw new IllegalArgumentException("Index name cannot be null or empty");
}
if (readCapacity == null || readCapacity <= 0) {
throw new IllegalArgumentException("Read capacity must be a positive number");
}
try {
LOGGER.info("Adding replica in region: " + replicaRegion.id() + " for table: " + tableName);
// Create a ReplicationGroupUpdate for adding a replica
ReplicationGroupUpdate replicationGroupUpdate = ReplicationGroupUpdate.builder()
.create(builder -> builder.regionName(replicaRegion.id())
.globalSecondaryIndexes(ReplicaGlobalSecondaryIndex.builder()
.indexName(indexName)
.provisionedThroughputOverride(ProvisionedThroughputOverride.builder()
.readCapacityUnits(readCapacity)
.build())
.build())
.build())
.build();
UpdateTableRequest updateTableRequest = UpdateTableRequest.builder()
.tableName(tableName)
.replicaUpdates(replicationGroupUpdate)
.build();
UpdateTableResponse response = dynamoDbClient.updateTable(updateTableRequest);
LOGGER.info("Replica addition initiated in region: " + replicaRegion.id());
return response;
} catch (DynamoDbException e) {
LOGGER.severe("Failed to add replica in region: " + replicaRegion.id() + " - " + e.getMessage());
throw e;
}
}
```
Remove a replica from a global table using AWS SDK for Java 2.x.
```
public static UpdateTableResponse removeReplica(
final DynamoDbClient dynamoDbClient, final String tableName, final Region replicaRegion) {
if (dynamoDbClient == null) {
throw new IllegalArgumentException("DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
if (replicaRegion == null) {
throw new IllegalArgumentException("Replica region cannot be null");
}
try {
LOGGER.info("Removing replica in region: " + replicaRegion.id() + " for table: " + tableName);
// Create a ReplicationGroupUpdate for removing a replica
ReplicationGroupUpdate replicationGroupUpdate = ReplicationGroupUpdate.builder()
.delete(builder -> builder.regionName(replicaRegion.id()).build())
.build();
UpdateTableRequest updateTableRequest = UpdateTableRequest.builder()
.tableName(tableName)
.replicaUpdates(replicationGroupUpdate)
.build();
UpdateTableResponse response = dynamoDbClient.updateTable(updateTableRequest);
LOGGER.info("Replica removal initiated in region: " + replicaRegion.id());
return response;
} catch (DynamoDbException e) {
LOGGER.severe("Failed to remove replica in region: " + replicaRegion.id() + " - " + e.getMessage());
throw e;
}
}
```
Add test items to verify replication using AWS SDK for Java 2.x.
```
public static PutItemResponse putTestItem(
final DynamoDbClient dynamoDbClient, final String tableName, final String artist, final String songTitle) {
if (dynamoDbClient == null) {
throw new IllegalArgumentException("DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
if (artist == null || artist.trim().isEmpty()) {
throw new IllegalArgumentException("Artist cannot be null or empty");
}
if (songTitle == null || songTitle.trim().isEmpty()) {
throw new IllegalArgumentException("Song title cannot be null or empty");
}
try {
LOGGER.info("Adding test item to table: " + tableName);
Map item = new HashMap<>();
item.put(
"Artist",
software.amazon.awssdk.services.dynamodb.model.AttributeValue.builder()
.s(artist)
.build());
item.put(
"SongTitle",
software.amazon.awssdk.services.dynamodb.model.AttributeValue.builder()
.s(songTitle)
.build());
PutItemRequest putItemRequest =
PutItemRequest.builder().tableName(tableName).item(item).build();
PutItemResponse response = dynamoDbClient.putItem(putItemRequest);
LOGGER.info("Test item added successfully");
return response;
} catch (DynamoDbException e) {
LOGGER.severe("Failed to add test item to table: " + tableName + " - " + e.getMessage());
throw e;
}
}
```
Describe global table configuration and replicas using AWS SDK for Java 2.x.
```
public static DescribeTableResponse describeTable(final DynamoDbClient dynamoDbClient, final String tableName) {
if (dynamoDbClient == null) {
throw new IllegalArgumentException("DynamoDB client cannot be null");
}
if (tableName == null || tableName.trim().isEmpty()) {
throw new IllegalArgumentException("Table name cannot be null or empty");
}
try {
LOGGER.info("Describing table: " + tableName);
DescribeTableRequest request =
DescribeTableRequest.builder().tableName(tableName).build();
DescribeTableResponse response = dynamoDbClient.describeTable(request);
LOGGER.info("Table status: " + response.table().tableStatus());
if (response.table().replicas() != null
&& !response.table().replicas().isEmpty()) {
LOGGER.info("Number of replicas: " + response.table().replicas().size());
response.table()
.replicas()
.forEach(replica -> LOGGER.info(
"Replica region: " + replica.regionName() + ", Status: " + replica.replicaStatus()));
}
return response;
} catch (ResourceNotFoundException e) {
LOGGER.severe("Table not found: " + tableName + " - " + e.getMessage());
throw e;
} catch (DynamoDbException e) {
LOGGER.severe("Failed to describe table: " + tableName + " - " + e.getMessage());
throw e;
}
}
```
Complete example of global table operations using AWS SDK for Java 2.x.
```
public static void exampleUsage(final Region sourceRegion, final Region replicaRegion) {
String tableName = "Music";
String indexName = "SongTitleIndex";
Long readCapacity = 15L;
// Create DynamoDB client for the source region
try (DynamoDbClient dynamoDbClient =
DynamoDbClient.builder().region(sourceRegion).build()) {
try {
// Step 1: Create the initial table with GSI and streams
LOGGER.info("Step 1: Creating table in source region: " + sourceRegion.id());
createTableWithGSI(dynamoDbClient, tableName, indexName);
// Step 2: Wait for table to become active
LOGGER.info("Step 2: Waiting for table to become active");
waitForTableActive(dynamoDbClient, tableName);
// Step 3: Add replica in destination region
LOGGER.info("Step 3: Adding replica in region: " + replicaRegion.id());
addReplica(dynamoDbClient, tableName, replicaRegion, indexName, readCapacity);
// Step 4: Wait a moment for replica creation to start
Thread.sleep(5000);
// Step 5: Describe table to view replica information
LOGGER.info("Step 5: Describing table to view replicas");
describeTable(dynamoDbClient, tableName);
// Step 6: Add a test item to verify replication
LOGGER.info("Step 6: Adding test item to verify replication");
putTestItem(dynamoDbClient, tableName, "TestArtist", "TestSong");
LOGGER.info("Global table setup completed successfully!");
LOGGER.info("You can verify replication by checking the item in region: " + replicaRegion.id());
// Step 7: Remove replica and clean up table
LOGGER.info("Step 7: Removing replica from region: " + replicaRegion.id());
removeReplica(dynamoDbClient, tableName, replicaRegion);
DeleteTableResponse deleteTableResponse = dynamoDbClient.deleteTable(
DeleteTableRequest.builder().tableName(tableName).build());
LOGGER.info("MREC global table demonstration completed successfully!");
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new RuntimeException("Thread was interrupted", e);
} catch (DynamoDbException e) {
LOGGER.severe("DynamoDB operation failed: " + e.getMessage());
throw e;
}
}
}
```
+ For API details, see the following topics in *AWS SDK for Java 2.x API Reference*.
+ [CreateTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/CreateTable)
+ [DescribeTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/DescribeTable)
+ [PutItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/PutItem)
+ [UpdateTable](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/UpdateTable)
### Detect PPE in images
The following code example shows how to build an app that uses Amazon Rekognition to detect Personal Protective Equipment (PPE) in images.
**SDK for Java 2.x**
Shows how to create an AWS Lambda function that detects images with Personal Protective Equipment.
For complete source code and instructions on how to set up and run, see the full example on [GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/usecases/creating_lambda_ppe).
**Services used in this example**
+ DynamoDB
+ Amazon Rekognition
+ Amazon S3
+ Amazon SES
### Monitor DynamoDB performance
The following code example shows how to configure an application's use of DynamoDB to monitor performance.
**SDK for Java 2.x**
This example shows how to configure a Java application to monitor the performance of DynamoDB. The application sends metric data to CloudWatch where you can monitor the performance.
For complete source code and instructions on how to set up and run, see the full example on [GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/usecases/monitor_dynamodb).
**Services used in this example**
+ CloudWatch
+ DynamoDB
### Perform advanced query operations
The following code example shows how to perform advanced query operations in DynamoDB.
+ Query tables using various filtering and condition techniques.
+ Implement pagination for large result sets.
+ Use Global Secondary Indexes for alternate access patterns.
+ Apply consistency controls based on application requirements.
**SDK for Java 2.x**
Query with strongly consistent reads using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import java.util.HashMap;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
public QueryResponse queryWithConsistentReads(
final String tableName,
final String partitionKeyName,
final String partitionKeyValue,
final boolean useConsistentRead) {
CodeSampleUtils.validateTableParameters(tableName, partitionKeyName, partitionKeyValue);
// Create expression attribute names for the column names
final Map expressionAttributeNames = new HashMap<>();
expressionAttributeNames.put(EXPRESSION_ATTRIBUTE_NAME_PK, partitionKeyName);
// Create expression attribute values for the column values
final Map expressionAttributeValues = new HashMap<>();
expressionAttributeValues.put(
EXPRESSION_ATTRIBUTE_VALUE_PK,
AttributeValue.builder().s(partitionKeyValue).build());
// Create the query request
final QueryRequest queryRequest = QueryRequest.builder()
.tableName(tableName)
.keyConditionExpression(KEY_CONDITION_EXPRESSION)
.expressionAttributeNames(expressionAttributeNames)
.expressionAttributeValues(expressionAttributeValues)
.consistentRead(useConsistentRead)
.build();
try {
final QueryResponse response = dynamoDbClient.query(queryRequest);
LOGGER.log(Level.INFO, "Query successful. Found {0} items", response.count());
return response;
} catch (ResourceNotFoundException e) {
LOGGER.log(Level.SEVERE, "Table not found: {0}", tableName);
throw e;
} catch (DynamoDbException e) {
LOGGER.log(Level.SEVERE, "Error querying with consistent reads", e);
throw e;
}
}
```
Query using a Global Secondary Index with AWS SDK for Java 2.x.
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import java.util.HashMap;
import java.util.Map;
public QueryResponse queryTable(
final String tableName, final String partitionKeyName, final String partitionKeyValue) {
CodeSampleUtils.validateTableParameters(tableName, partitionKeyName, partitionKeyValue);
// Create expression attribute names for the column names
final Map expressionAttributeNames = new HashMap<>();
expressionAttributeNames.put(EXPRESSION_ATTRIBUTE_NAME_PK, partitionKeyName);
// Create expression attribute values for the column values
final Map expressionAttributeValues = new HashMap<>();
expressionAttributeValues.put(
EXPRESSION_ATTRIBUTE_VALUE_PK,
AttributeValue.builder().s(partitionKeyValue).build());
// Create the query request
final QueryRequest queryRequest = QueryRequest.builder()
.tableName(tableName)
.keyConditionExpression(KEY_CONDITION_EXPRESSION)
.expressionAttributeNames(expressionAttributeNames)
.expressionAttributeValues(expressionAttributeValues)
.build();
try {
final QueryResponse response = dynamoDbClient.query(queryRequest);
System.out.println("Query on base table successful. Found " + response.count() + " items");
return response;
} catch (ResourceNotFoundException e) {
System.err.format("Error: The Amazon DynamoDB table \"%s\" can't be found.\n", tableName);
throw new DynamoDbQueryException("Table not found: " + tableName, e);
} catch (DynamoDbException e) {
System.err.println("Error querying base table: " + e.getMessage());
throw new DynamoDbQueryException("Failed to execute query on base table", e);
}
}
/**
* Queries a DynamoDB Global Secondary Index (GSI) by partition key.
*
* @param tableName The name of the DynamoDB table
* @param indexName The name of the GSI
* @param partitionKeyName The name of the GSI partition key attribute
* @param partitionKeyValue The value of the GSI partition key to query
* @return The query response from DynamoDB
* @throws ResourceNotFoundException if the table or index doesn't exist
* @throws DynamoDbException if the query fails
*/
public QueryResponse queryGlobalSecondaryIndex(
final String tableName, final String indexName, final String partitionKeyName, final String partitionKeyValue) {
CodeSampleUtils.validateTableParameters(tableName, partitionKeyName, partitionKeyValue);
CodeSampleUtils.validateStringParameter("Index name", indexName);
// Create expression attribute names for the column names
final Map expressionAttributeNames = new HashMap<>();
expressionAttributeNames.put(EXPRESSION_ATTRIBUTE_NAME_IK, partitionKeyName);
// Create expression attribute values for the column values
final Map expressionAttributeValues = new HashMap<>();
expressionAttributeValues.put(
EXPRESSION_ATTRIBUTE_VALUE_IK,
AttributeValue.builder().s(partitionKeyValue).build());
// Create the query request
final QueryRequest queryRequest = QueryRequest.builder()
.tableName(tableName)
.indexName(indexName)
.keyConditionExpression(GSI_KEY_CONDITION_EXPRESSION)
.expressionAttributeNames(expressionAttributeNames)
.expressionAttributeValues(expressionAttributeValues)
.build();
try {
final QueryResponse response = dynamoDbClient.query(queryRequest);
System.out.println("Query on GSI successful. Found " + response.count() + " items");
return response;
} catch (ResourceNotFoundException e) {
System.err.format(
"Error: The Amazon DynamoDB table \"%s\" or index \"%s\" can't be found.\n", tableName, indexName);
throw new DynamoDbQueryException("Table or index not found: " + tableName + "/" + indexName, e);
} catch (DynamoDbException e) {
System.err.println("Error querying GSI: " + e.getMessage());
throw new DynamoDbQueryException("Failed to execute query on GSI", e);
}
}
```
Query with pagination using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public List> queryWithPagination(
final String tableName, final String partitionKeyName, final String partitionKeyValue, final int pageSize) {
CodeSampleUtils.validateTableParameters(tableName, partitionKeyName, partitionKeyValue);
CodeSampleUtils.validatePositiveInteger("Page size", pageSize);
// Create expression attribute names for the column names
final Map expressionAttributeNames = new HashMap<>();
expressionAttributeNames.put(EXPRESSION_ATTRIBUTE_NAME_PK, partitionKeyName);
// Create expression attribute values for the column values
final Map expressionAttributeValues = new HashMap<>();
expressionAttributeValues.put(
EXPRESSION_ATTRIBUTE_VALUE_PK,
AttributeValue.builder().s(partitionKeyValue).build());
// Create the query request
QueryRequest.Builder queryRequestBuilder = QueryRequest.builder()
.tableName(tableName)
.keyConditionExpression(KEY_CONDITION_EXPRESSION)
.expressionAttributeNames(expressionAttributeNames)
.expressionAttributeValues(expressionAttributeValues)
.limit(pageSize);
// List to store all items from all pages
final List> allItems = new ArrayList<>();
// Map to store the last evaluated key for pagination
Map lastEvaluatedKey = null;
int pageNumber = 1;
try {
do {
// If we have a last evaluated key, use it for the next page
if (lastEvaluatedKey != null) {
queryRequestBuilder.exclusiveStartKey(lastEvaluatedKey);
}
// Execute the query
final QueryResponse response = dynamoDbClient.query(queryRequestBuilder.build());
// Process the current page of results
final List> pageItems = response.items();
allItems.addAll(pageItems);
// Get the last evaluated key for the next page
lastEvaluatedKey = response.lastEvaluatedKey();
if (lastEvaluatedKey != null && lastEvaluatedKey.isEmpty()) {
lastEvaluatedKey = null;
}
System.out.println("Page " + pageNumber + ": Retrieved " + pageItems.size() + " items (Running total: "
+ allItems.size() + ")");
pageNumber++;
} while (lastEvaluatedKey != null);
System.out.println("Query with pagination complete. Retrieved a total of " + allItems.size()
+ " items across " + (pageNumber - 1) + " pages");
return allItems;
} catch (ResourceNotFoundException e) {
System.err.format("Error: The Amazon DynamoDB table \"%s\" can't be found.\n", tableName);
throw e;
} catch (DynamoDbException e) {
System.err.println("Error querying with pagination: " + e.getMessage());
throw e;
}
}
```
Query with complex filters using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import java.util.HashMap;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
public QueryResponse queryWithComplexFilter(
final String tableName,
final String partitionKeyName,
final String partitionKeyValue,
final String statusAttrName,
final String activeStatus,
final String pendingStatus,
final String priceAttrName,
final double minPrice,
final double maxPrice,
final String categoryAttrName) {
// Validate parameters
CodeSampleUtils.validateTableParameters(tableName, partitionKeyName, partitionKeyValue);
CodeSampleUtils.validateStringParameter("Status attribute name", statusAttrName);
CodeSampleUtils.validateStringParameter("Active status", activeStatus);
CodeSampleUtils.validateStringParameter("Pending status", pendingStatus);
CodeSampleUtils.validateStringParameter("Price attribute name", priceAttrName);
CodeSampleUtils.validateStringParameter("Category attribute name", categoryAttrName);
CodeSampleUtils.validateNumericRange("Minimum price", minPrice, 0.0, Double.MAX_VALUE);
CodeSampleUtils.validateNumericRange("Maximum price", maxPrice, minPrice, Double.MAX_VALUE);
// Create expression attribute names for the column names
final Map expressionAttributeNames = new HashMap<>();
expressionAttributeNames.put("#pk", partitionKeyName);
expressionAttributeNames.put(EXPRESSION_ATTRIBUTE_NAME_STATUS, statusAttrName);
expressionAttributeNames.put(EXPRESSION_ATTRIBUTE_NAME_PRICE, priceAttrName);
expressionAttributeNames.put(EXPRESSION_ATTRIBUTE_NAME_CATEGORY, categoryAttrName);
// Create expression attribute values for the column values
final Map expressionAttributeValues = new HashMap<>();
expressionAttributeValues.put(
":pkValue", AttributeValue.builder().s(partitionKeyValue).build());
expressionAttributeValues.put(
EXPRESSION_ATTRIBUTE_VALUE_ACTIVE,
AttributeValue.builder().s(activeStatus).build());
expressionAttributeValues.put(
EXPRESSION_ATTRIBUTE_VALUE_PENDING,
AttributeValue.builder().s(pendingStatus).build());
expressionAttributeValues.put(
EXPRESSION_ATTRIBUTE_VALUE_MIN_PRICE,
AttributeValue.builder().n(String.valueOf(minPrice)).build());
expressionAttributeValues.put(
EXPRESSION_ATTRIBUTE_VALUE_MAX_PRICE,
AttributeValue.builder().n(String.valueOf(maxPrice)).build());
// Create the query request
final QueryRequest queryRequest = QueryRequest.builder()
.tableName(tableName)
.keyConditionExpression(KEY_CONDITION_EXPRESSION)
.filterExpression(FILTER_EXPRESSION)
.expressionAttributeNames(expressionAttributeNames)
.expressionAttributeValues(expressionAttributeValues)
.build();
return dynamoDbClient.query(queryRequest);
}
```
Query with a dynamically constructed filter expression using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import java.util.HashMap;
import java.util.Map;
public static QueryResponse queryWithDynamicFilter(
final String tableName,
final String partitionKeyName,
final String partitionKeyValue,
final Map filterCriteria,
final Region region,
final DynamoDbClient dynamoDbClient) {
validateParameters(tableName, partitionKeyName, partitionKeyValue, filterCriteria);
DynamoDbClient ddbClient = dynamoDbClient;
boolean shouldClose = false;
try {
if (ddbClient == null) {
ddbClient = createClient(region);
shouldClose = true;
}
final QueryWithDynamicFilter queryHelper = new QueryWithDynamicFilter(ddbClient);
return queryHelper.queryWithDynamicFilter(tableName, partitionKeyName, partitionKeyValue, filterCriteria);
} catch (ResourceNotFoundException e) {
System.err.println("Table not found: " + tableName);
throw e;
} catch (DynamoDbException e) {
System.err.println("Failed to execute dynamic filter query: " + e.getMessage());
throw e;
} catch (Exception e) {
System.err.println("Unexpected error during query: " + e.getMessage());
throw e;
} finally {
if (shouldClose && ddbClient != null) {
ddbClient.close();
}
}
}
public static void main(String[] args) {
final String usage =
"""
Usage:
[region]
Where:
tableName - The Amazon DynamoDB table to query.
partitionKeyName - The name of the partition key attribute.
partitionKeyValue - The value of the partition key to query.
filterAttrName - The name of the attribute to filter on.
filterAttrValue - The value to filter by.
region (optional) - The AWS region where the table exists. (Default: us-east-1)
""";
if (args.length < 5) {
System.out.println(usage);
System.exit(1);
}
final String tableName = args[0];
final String partitionKeyName = args[1];
final String partitionKeyValue = args[2];
final String filterAttrName = args[3];
final String filterAttrValue = args[4];
final Region region = args.length > 5 ? Region.of(args[5]) : Region.US_EAST_1;
System.out.println("Querying items with dynamic filter: " + filterAttrName + " = " + filterAttrValue);
try {
// Using the builder pattern to create and execute the query
final QueryResponse response = new DynamicFilterQueryBuilder()
.withTableName(tableName)
.withPartitionKeyName(partitionKeyName)
.withPartitionKeyValue(partitionKeyValue)
.withFilterCriterion(filterAttrName, filterAttrValue)
.withRegion(region)
.execute();
// Process the results
System.out.println("Found " + response.count() + " items:");
response.items().forEach(item -> System.out.println(item));
// Demonstrate multiple filter criteria
System.out.println("\nNow querying with multiple filter criteria:");
Map multipleFilters = new HashMap<>();
multipleFilters.put(filterAttrName, filterAttrValue);
multipleFilters.put("status", "active");
final QueryResponse multiFilterResponse = new DynamicFilterQueryBuilder()
.withTableName(tableName)
.withPartitionKeyName(partitionKeyName)
.withPartitionKeyValue(partitionKeyValue)
.withFilterCriteria(multipleFilters)
.withRegion(region)
.execute();
System.out.println("Found " + multiFilterResponse.count() + " items with multiple filters:");
multiFilterResponse.items().forEach(item -> System.out.println(item));
} catch (IllegalArgumentException e) {
System.err.println("Invalid input: " + e.getMessage());
System.exit(1);
} catch (ResourceNotFoundException e) {
System.err.println("Table not found: " + tableName);
System.exit(1);
} catch (DynamoDbException e) {
System.err.println("DynamoDB error: " + e.getMessage());
System.exit(1);
} catch (Exception e) {
System.err.println("Unexpected error: " + e.getMessage());
System.exit(1);
}
}
```
Query with a filter expression and limit using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import java.util.HashMap;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
public QueryResponse queryWithFilterAndLimit(
final String tableName,
final String partitionKeyName,
final String partitionKeyValue,
final String filterAttrName,
final String filterAttrValue,
final int limit) {
CodeSampleUtils.validateTableParameters(tableName, partitionKeyName, partitionKeyValue);
CodeSampleUtils.validateStringParameter("Filter attribute name", filterAttrName);
CodeSampleUtils.validateStringParameter("Filter attribute value", filterAttrValue);
CodeSampleUtils.validatePositiveInteger("Limit", limit);
// Create expression attribute names for the column names
final Map expressionAttributeNames = new HashMap<>();
expressionAttributeNames.put(EXPRESSION_ATTRIBUTE_NAME_PK, partitionKeyName);
expressionAttributeNames.put(EXPRESSION_ATTRIBUTE_NAME_FILTER, filterAttrName);
// Create expression attribute values for the column values
final Map expressionAttributeValues = new HashMap<>();
expressionAttributeValues.put(
EXPRESSION_ATTRIBUTE_VALUE_PK,
AttributeValue.builder().s(partitionKeyValue).build());
expressionAttributeValues.put(
EXPRESSION_ATTRIBUTE_VALUE_FILTER,
AttributeValue.builder().s(filterAttrValue).build());
// Create the filter expression
final String filterExpression = "#filterAttr = :filterValue";
// Create the query request
final QueryRequest queryRequest = QueryRequest.builder()
.tableName(tableName)
.keyConditionExpression(KEY_CONDITION_EXPRESSION)
.filterExpression(filterExpression)
.expressionAttributeNames(expressionAttributeNames)
.expressionAttributeValues(expressionAttributeValues)
.limit(limit)
.build();
try {
final QueryResponse response = dynamoDbClient.query(queryRequest);
LOGGER.log(Level.INFO, "Query with filter and limit successful. Found {0} items", response.count());
LOGGER.log(
Level.INFO, "ScannedCount: {0} (total items evaluated before filtering)", response.scannedCount());
return response;
} catch (ResourceNotFoundException e) {
LOGGER.log(Level.SEVERE, "Table not found: {0}", tableName);
throw e;
} catch (DynamoDbException e) {
LOGGER.log(Level.SEVERE, "Error querying with filter and limit: {0}", e.getMessage());
throw e;
}
}
```
+ For API details, see [Query](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/Query) in *AWS SDK for Java 2.x API Reference*.
### Perform list operations
The following code example shows how to perform list operations in DynamoDB.
+ Add elements to a list attribute.
+ Remove elements from a list attribute.
+ Update specific elements in a list by index.
+ Use list append and list index functions.
**SDK for Java 2.x**
Demonstrate list operations using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.GetItemRequest;
import software.amazon.awssdk.services.dynamodb.model.GetItemResponse;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemRequest;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemResponse;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Appends items to a list attribute.
*
* This method demonstrates how to use the list_append function to add
* items to the end of a list attribute.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to update
* @param listAttributeName The name of the list attribute
* @param itemsToAppend The items to append to the list
* @return The response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static UpdateItemResponse appendToList(
DynamoDbClient dynamoDbClient,
String tableName,
Map key,
String listAttributeName,
List itemsToAppend) {
// Create a list value from the items to append
AttributeValue listValue = AttributeValue.builder().l(itemsToAppend).build();
// Define the update parameters
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("SET #attrName = list_append(if_not_exists(#attrName, :emptyList), :newItems)")
.expressionAttributeNames(Map.of("#attrName", listAttributeName))
.expressionAttributeValues(Map.of(
":newItems",
listValue,
":emptyList",
AttributeValue.builder().l(new ArrayList()).build()))
.returnValues("UPDATED_NEW")
.build();
// Perform the update operation
return dynamoDbClient.updateItem(request);
}
/**
* Prepends items to a list attribute.
*
* This method demonstrates how to use the list_append function to add
* items to the beginning of a list attribute.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to update
* @param listAttributeName The name of the list attribute
* @param itemsToPrepend The items to prepend to the list
* @return The response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static UpdateItemResponse prependToList(
DynamoDbClient dynamoDbClient,
String tableName,
Map key,
String listAttributeName,
List itemsToPrepend) {
// Create a list value from the items to prepend
AttributeValue listValue = AttributeValue.builder().l(itemsToPrepend).build();
// Define the update parameters
// Note: To prepend, we put the new items first in the list_append function
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("SET #attrName = list_append(:newItems, if_not_exists(#attrName, :emptyList))")
.expressionAttributeNames(Map.of("#attrName", listAttributeName))
.expressionAttributeValues(Map.of(
":newItems",
listValue,
":emptyList",
AttributeValue.builder().l(new ArrayList()).build()))
.returnValues("UPDATED_NEW")
.build();
// Perform the update operation
return dynamoDbClient.updateItem(request);
}
/**
* Updates a specific element in a list attribute.
*
* This method demonstrates how to update a specific element in a list
* by its index.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to update
* @param listAttributeName The name of the list attribute
* @param index The index of the element to update
* @param newValue The new value for the element
* @return The response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static UpdateItemResponse updateListElement(
DynamoDbClient dynamoDbClient,
String tableName,
Map key,
String listAttributeName,
int index,
AttributeValue newValue) {
// Define the update parameters
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("SET #attrName[" + index + "] = :newValue")
.expressionAttributeNames(Map.of("#attrName", listAttributeName))
.expressionAttributeValues(Map.of(":newValue", newValue))
.returnValues("UPDATED_NEW")
.build();
// Perform the update operation
return dynamoDbClient.updateItem(request);
}
/**
* Removes a specific element from a list attribute.
*
* This method demonstrates how to remove a specific element from a list
* by its index.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to update
* @param listAttributeName The name of the list attribute
* @param index The index of the element to remove
* @return The response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static UpdateItemResponse removeListElement(
DynamoDbClient dynamoDbClient,
String tableName,
Map key,
String listAttributeName,
int index) {
// Define the update parameters
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("REMOVE #attrName[" + index + "]")
.expressionAttributeNames(Map.of("#attrName", listAttributeName))
.returnValues("UPDATED_NEW")
.build();
// Perform the update operation
return dynamoDbClient.updateItem(request);
}
/**
* Gets the current value of a list attribute.
*
* Helper method to retrieve the current value of a list attribute.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to get
* @param listAttributeName The name of the list attribute
* @return The list attribute value or null if not found
* @throws DynamoDbException if an error occurs during the operation
*/
public static List getListAttribute(
DynamoDbClient dynamoDbClient, String tableName, Map key, String listAttributeName) {
// Define the get parameters
GetItemRequest request = GetItemRequest.builder()
.tableName(tableName)
.key(key)
.projectionExpression(listAttributeName)
.build();
try {
// Perform the get operation
GetItemResponse response = dynamoDbClient.getItem(request);
// Return the list attribute if it exists, otherwise null
if (response.item() != null && response.item().containsKey(listAttributeName)) {
return response.item().get(listAttributeName).l();
}
return null;
} catch (DynamoDbException e) {
throw DynamoDbException.builder()
.message("Failed to get list attribute: " + e.getMessage())
.cause(e)
.build();
}
}
```
Example usage of list operations with AWS SDK for Java 2.x.
```
public static void exampleUsage(DynamoDbClient dynamoDbClient, String tableName) {
// Example key
Map key = new HashMap<>();
key.put("ProductId", AttributeValue.builder().s("P12345").build());
System.out.println("Demonstrating list operations in DynamoDB");
try {
// Example 1: Append items to a list
System.out.println("\nExample 1: Appending items to a list");
List tagsToAppend = List.of(
AttributeValue.builder().s("Electronics").build(),
AttributeValue.builder().s("Gadget").build());
UpdateItemResponse appendResponse = appendToList(dynamoDbClient, tableName, key, "Tags", tagsToAppend);
System.out.println("Updated list attribute: " + appendResponse.attributes());
// Example 2: Prepend items to a list
System.out.println("\nExample 2: Prepending items to a list");
List tagsToPrepend = List.of(
AttributeValue.builder().s("Featured").build(),
AttributeValue.builder().s("New").build());
UpdateItemResponse prependResponse = prependToList(dynamoDbClient, tableName, key, "Tags", tagsToPrepend);
System.out.println("Updated list attribute: " + prependResponse.attributes());
// Example 3: Update a specific element in a list
System.out.println("\nExample 3: Updating a specific element in a list");
UpdateItemResponse updateResponse = updateListElement(
dynamoDbClient,
tableName,
key,
"Tags",
0,
AttributeValue.builder().s("BestSeller").build());
System.out.println("Updated list attribute: " + updateResponse.attributes());
// Example 4: Remove a specific element from a list
System.out.println("\nExample 4: Removing a specific element from a list");
UpdateItemResponse removeResponse = removeListElement(dynamoDbClient, tableName, key, "Tags", 1);
System.out.println("Updated list attribute: " + removeResponse.attributes());
// Example 5: Get the current value of a list attribute
System.out.println("\nExample 5: Getting the current value of a list attribute");
List currentList = getListAttribute(dynamoDbClient, tableName, key, "Tags");
if (currentList != null) {
System.out.println("Current list attribute:");
for (int i = 0; i < currentList.size(); i++) {
System.out.println(" [" + i + "]: " + currentList.get(i).s());
}
} else {
System.out.println("List attribute not found");
}
// Explain list operations
System.out.println("\nKey points about DynamoDB list operations:");
System.out.println("1. Lists are ordered collections of attributes");
System.out.println("2. Use list_append to add items to a list");
System.out.println("3. To append items, use list_append(existingList, newItems)");
System.out.println("4. To prepend items, use list_append(newItems, existingList)");
System.out.println("5. Use index notation (list[0]) to access or update specific elements");
System.out.println("6. Use REMOVE to delete elements from a list");
System.out.println("7. List indices are zero-based");
System.out.println("8. Use if_not_exists to handle the case where the list doesn't exist yet");
} catch (DynamoDbException e) {
System.err.println("Error: " + e.getMessage());
e.printStackTrace();
}
}
```
+ For API details, see [UpdateItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/UpdateItem) in *AWS SDK for Java 2.x API Reference*.
### Perform map operations
The following code example shows how to perform map operations in DynamoDB.
+ Add and update nested attributes in map structures.
+ Remove specific fields from maps.
+ Work with deeply nested map attributes.
**SDK for Java 2.x**
Demonstrate map operations using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.GetItemRequest;
import software.amazon.awssdk.services.dynamodb.model.GetItemResponse;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemRequest;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemResponse;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Updates a map attribute that may not exist.
*
* This method demonstrates how to safely update a map attribute
* by using if_not_exists to handle the case where the map doesn't exist yet.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to update
* @param mapName The name of the map attribute
* @param mapKey The key within the map to update
* @param value The value to set
* @return The response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static UpdateItemResponse updateMapAttributeSafe(
DynamoDbClient dynamoDbClient,
String tableName,
Map key,
String mapName,
String mapKey,
AttributeValue value) {
// Create an empty map to use if the map doesn't exist
Map emptyMap = new HashMap<>();
AttributeValue emptyMapValue = AttributeValue.builder().m(emptyMap).build();
// Define the update parameters
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("SET #mapName = if_not_exists(#mapName, :emptyMap), #mapName.#mapKey = :value")
.expressionAttributeNames(Map.of(
"#mapName", mapName,
"#mapKey", mapKey))
.expressionAttributeValues(Map.of(
":value",
value,
":emptyMap",
AttributeValue.builder().m(new HashMap<>()).build()))
.returnValues("UPDATED_NEW")
.build();
// Perform the update operation
return dynamoDbClient.updateItem(request);
}
/**
* Adds an attribute to a nested map.
*
* This method demonstrates how to update a nested attribute without
* overwriting the entire map.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to update
* @param path The path to the nested attribute as a list
* @param value The value to set
* @return The response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static UpdateItemResponse addToNestedMap(
DynamoDbClient dynamoDbClient,
String tableName,
Map key,
List path,
AttributeValue value) {
// Create expression attribute names for each part of the path
Map expressionAttributeNames = new HashMap<>();
for (int i = 0; i < path.size(); i++) {
expressionAttributeNames.put("#attr" + i, path.get(i));
}
// Build the attribute path using the expression attribute names
StringBuilder attributePathExpression = new StringBuilder();
for (int i = 0; i < path.size(); i++) {
if (i > 0) {
attributePathExpression.append(".");
}
attributePathExpression.append("#attr").append(i);
}
// Define the update parameters
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("SET " + attributePathExpression.toString() + " = :value")
.expressionAttributeNames(expressionAttributeNames)
.expressionAttributeValues(Map.of(":value", value))
.returnValues("UPDATED_NEW")
.build();
// Perform the update operation
return dynamoDbClient.updateItem(request);
}
/**
* Removes an attribute from a map.
*
* This method demonstrates how to remove a specific attribute from a map.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to update
* @param mapName The name of the map attribute
* @param mapKey The key within the map to remove
* @return The response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static UpdateItemResponse removeMapAttribute(
DynamoDbClient dynamoDbClient,
String tableName,
Map key,
String mapName,
String mapKey) {
// Define the update parameters
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("REMOVE #mapName.#mapKey")
.expressionAttributeNames(Map.of(
"#mapName", mapName,
"#mapKey", mapKey))
.returnValues("UPDATED_NEW")
.build();
// Perform the update operation
return dynamoDbClient.updateItem(request);
}
/**
* Creates a map with multiple attributes in a single operation.
*
* This method demonstrates how to create a map with multiple attributes
* in a single update operation.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to update
* @param mapName The name of the map attribute
* @param attributes The attributes to set in the map
* @return The response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static UpdateItemResponse createMapWithAttributes(
DynamoDbClient dynamoDbClient,
String tableName,
Map key,
String mapName,
Map attributes) {
// Create a map value from the attributes
AttributeValue mapValue = AttributeValue.builder().m(attributes).build();
// Define the update parameters
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("SET #mapName = :mapValue")
.expressionAttributeNames(Map.of("#mapName", mapName))
.expressionAttributeValues(Map.of(":mapValue", mapValue))
.returnValues("UPDATED_NEW")
.build();
// Perform the update operation
return dynamoDbClient.updateItem(request);
}
/**
* Gets the current value of a map attribute.
*
* Helper method to retrieve the current value of a map attribute.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to get
* @param mapName The name of the map attribute
* @return The map attribute value or null if not found
* @throws DynamoDbException if an error occurs during the operation
*/
public static Map getMapAttribute(
DynamoDbClient dynamoDbClient, String tableName, Map key, String mapName) {
// Define the get parameters
GetItemRequest request = GetItemRequest.builder()
.tableName(tableName)
.key(key)
.projectionExpression(mapName)
.build();
try {
// Perform the get operation
GetItemResponse response = dynamoDbClient.getItem(request);
// Return the map attribute if it exists, otherwise null
if (response.item() != null && response.item().containsKey(mapName)) {
return response.item().get(mapName).m();
}
return null;
} catch (DynamoDbException e) {
throw DynamoDbException.builder()
.message("Failed to get map attribute: " + e.getMessage())
.cause(e)
.build();
}
}
```
Example usage of map operations with AWS SDK for Java 2.x.
```
public static void exampleUsage(DynamoDbClient dynamoDbClient, String tableName) {
// Example key
Map key = new HashMap<>();
key.put("ProductId", AttributeValue.builder().s("P12345").build());
System.out.println("Demonstrating map operations in DynamoDB");
try {
// Example 1: Create a map with multiple attributes
System.out.println("\nExample 1: Creating a map with multiple attributes");
Map productDetails = new HashMap<>();
productDetails.put("Color", AttributeValue.builder().s("Red").build());
productDetails.put("Weight", AttributeValue.builder().n("2.5").build());
productDetails.put(
"Dimensions", AttributeValue.builder().s("10x20x5").build());
UpdateItemResponse createResponse =
createMapWithAttributes(dynamoDbClient, tableName, key, "Details", productDetails);
System.out.println("Created map attribute: " + createResponse.attributes());
// Example 2: Update a specific attribute in a map
System.out.println("\nExample 2: Updating a specific attribute in a map");
UpdateItemResponse updateResponse = updateMapAttributeSafe(
dynamoDbClient,
tableName,
key,
"Details",
"Color",
AttributeValue.builder().s("Blue").build());
System.out.println("Updated map attribute: " + updateResponse.attributes());
// Example 3: Add an attribute to a nested map
System.out.println("\nExample 3: Adding an attribute to a nested map");
UpdateItemResponse nestedResponse = addToNestedMap(
dynamoDbClient,
tableName,
key,
List.of("Specifications", "Technical", "Resolution"),
AttributeValue.builder().s("1920x1080").build());
System.out.println("Added to nested map: " + nestedResponse.attributes());
// Example 4: Remove an attribute from a map
System.out.println("\nExample 4: Removing an attribute from a map");
UpdateItemResponse removeResponse =
removeMapAttribute(dynamoDbClient, tableName, key, "Details", "Dimensions");
System.out.println("Updated map after removal: " + removeResponse.attributes());
// Example 5: Get the current value of a map attribute
System.out.println("\nExample 5: Getting the current value of a map attribute");
Map currentMap = getMapAttribute(dynamoDbClient, tableName, key, "Details");
if (currentMap != null) {
System.out.println("Current map attribute:");
for (Map.Entry entry : currentMap.entrySet()) {
System.out.println(" " + entry.getKey() + ": " + entry.getValue());
}
} else {
System.out.println("Map attribute not found");
}
// Explain map operations
System.out.println("\nKey points about DynamoDB map operations:");
System.out.println("1. Maps are unordered collections of name-value pairs");
System.out.println("2. Use dot notation (map.key) to access or update specific attributes");
System.out.println("3. You can update individual attributes without overwriting the entire map");
System.out.println("4. Maps can be nested to create complex data structures");
System.out.println("5. Use REMOVE to delete attributes from a map");
System.out.println("6. You can create a map with multiple attributes in a single operation");
System.out.println("7. Map keys are case-sensitive");
} catch (DynamoDbException e) {
System.err.println("Error: " + e.getMessage());
e.printStackTrace();
}
}
```
+ For API details, see [UpdateItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/UpdateItem) in *AWS SDK for Java 2.x API Reference*.
### Perform set operations
The following code example shows how to perform set operations in DynamoDB.
+ Add elements to a set attribute.
+ Remove elements from a set attribute.
+ Use ADD and DELETE operations with sets.
**SDK for Java 2.x**
Demonstrate set operations using AWS SDK for Java 2.x.
```
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.GetItemRequest;
import software.amazon.awssdk.services.dynamodb.model.GetItemResponse;
import software.amazon.awssdk.services.dynamodb.model.ReturnValue;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemRequest;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemResponse;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
/**
* Adds values to a string set attribute.
*
* This method demonstrates how to use the ADD operation to add values
* to a string set attribute.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to update
* @param setAttributeName The name of the set attribute
* @param valuesToAdd The values to add to the set
* @return The response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static UpdateItemResponse addToStringSet(
DynamoDbClient dynamoDbClient,
String tableName,
Map key,
String setAttributeName,
Set valuesToAdd) {
// Create a string set value from the values to add
AttributeValue setValue = AttributeValue.builder().ss(valuesToAdd).build();
// Define the update parameters
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("ADD #setAttr :valuesToAdd")
.expressionAttributeNames(Map.of("#setAttr", setAttributeName))
.expressionAttributeValues(Map.of(":valuesToAdd", setValue))
.returnValues(ReturnValue.UPDATED_NEW)
.build();
// Perform the update operation
return dynamoDbClient.updateItem(request);
}
/**
* Adds values to a number set attribute.
*
* This method demonstrates how to use the ADD operation to add values
* to a number set attribute.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to update
* @param setAttributeName The name of the set attribute
* @param valuesToAdd The values to add to the set
* @return The response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static UpdateItemResponse addToNumberSet(
DynamoDbClient dynamoDbClient,
String tableName,
Map key,
String setAttributeName,
Set valuesToAdd) {
// Convert numbers to strings for DynamoDB
Set stringValues = new HashSet<>();
for (Number value : valuesToAdd) {
stringValues.add(value.toString());
}
// Create a number set value from the values to add
AttributeValue setValue = AttributeValue.builder().ns(stringValues).build();
// Define the update parameters
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("ADD #setAttr :valuesToAdd")
.expressionAttributeNames(Map.of("#setAttr", setAttributeName))
.expressionAttributeValues(Map.of(":valuesToAdd", setValue))
.returnValues(ReturnValue.UPDATED_NEW)
.build();
// Perform the update operation
return dynamoDbClient.updateItem(request);
}
/**
* Removes values from a set attribute.
*
* This method demonstrates how to use the DELETE operation to remove values
* from a set attribute.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to update
* @param setAttributeName The name of the set attribute
* @param valuesToRemove The values to remove from the set
* @param isNumberSet Whether the set is a number set (true) or string set (false)
* @return The response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static UpdateItemResponse removeFromSet(
DynamoDbClient dynamoDbClient,
String tableName,
Map key,
String setAttributeName,
Set valuesToRemove,
boolean isNumberSet) {
AttributeValue setValue;
if (isNumberSet) {
// Convert numbers to strings for DynamoDB
Set stringValues = new HashSet<>();
for (Object value : valuesToRemove) {
if (value instanceof Number) {
stringValues.add(value.toString());
} else {
throw new IllegalArgumentException("Values must be numbers for a number set");
}
}
setValue = AttributeValue.builder().ns(stringValues).build();
} else {
// Convert objects to strings for DynamoDB
Set stringValues = new HashSet<>();
for (Object value : valuesToRemove) {
stringValues.add(value.toString());
}
setValue = AttributeValue.builder().ss(stringValues).build();
}
// Define the update parameters
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("DELETE #setAttr :valuesToRemove")
.expressionAttributeNames(Map.of("#setAttr", setAttributeName))
.expressionAttributeValues(Map.of(":valuesToRemove", setValue))
.returnValues(ReturnValue.UPDATED_NEW)
.build();
// Perform the update operation
return dynamoDbClient.updateItem(request);
}
/**
* Checks if a value exists in a set attribute.
*
* This method demonstrates how to use the contains function to check
* if a value exists in a set attribute.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to check
* @param setAttributeName The name of the set attribute
* @param valueToCheck The value to check for
* @return Map containing the result of the check
* @throws DynamoDbException if an error occurs during the operation
*/
public static Map checkIfValueInSet(
DynamoDbClient dynamoDbClient,
String tableName,
Map key,
String setAttributeName,
String valueToCheck) {
Map result = new HashMap<>();
try {
// Define the update parameters with a condition expression
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("SET #tempAttr = :tempVal")
.conditionExpression("contains(#setAttr, :valueToCheck)")
.expressionAttributeNames(Map.of("#setAttr", setAttributeName, "#tempAttr", "TempAttribute"))
.expressionAttributeValues(Map.of(
":valueToCheck", AttributeValue.builder().s(valueToCheck).build(),
":tempVal", AttributeValue.builder().s("TempValue").build()))
.returnValues(ReturnValue.UPDATED_NEW)
.build();
// Attempt the update operation
dynamoDbClient.updateItem(request);
// If we get here, the condition was met
result.put("exists", true);
result.put("message", "Value '" + valueToCheck + "' exists in the set");
// Clean up the temporary attribute
UpdateItemRequest cleanupRequest = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("REMOVE #tempAttr")
.expressionAttributeNames(Map.of("#tempAttr", "TempAttribute"))
.build();
dynamoDbClient.updateItem(cleanupRequest);
} catch (DynamoDbException e) {
if (e.getMessage().contains("ConditionalCheckFailed")) {
// The condition was not met
result.put("exists", false);
result.put("message", "Value '" + valueToCheck + "' does not exist in the set");
} else {
// Some other error occurred
result.put("exists", false);
result.put("message", "Error checking set: " + e.getMessage());
result.put("error", e.getClass().getSimpleName());
}
}
return result;
}
/**
* Creates a set with multiple values in a single operation.
*
* This method demonstrates how to create a set with multiple values
* in a single update operation.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to update
* @param setAttributeName The name of the set attribute
* @param setValues The values to include in the set
* @param isNumberSet Whether to create a number set (true) or string set (false)
* @return The response from DynamoDB
* @throws DynamoDbException if an error occurs during the operation
*/
public static UpdateItemResponse createSetWithValues(
DynamoDbClient dynamoDbClient,
String tableName,
Map key,
String setAttributeName,
Set setValues,
boolean isNumberSet) {
AttributeValue setValue;
if (isNumberSet) {
// Convert numbers to strings for DynamoDB
Set stringValues = new HashSet<>();
for (Object value : setValues) {
if (value instanceof Number) {
stringValues.add(value.toString());
} else {
throw new IllegalArgumentException("Values must be numbers for a number set");
}
}
setValue = AttributeValue.builder().ns(stringValues).build();
} else {
// Convert objects to strings for DynamoDB
Set stringValues = new HashSet<>();
for (Object value : setValues) {
stringValues.add(value.toString());
}
setValue = AttributeValue.builder().ss(stringValues).build();
}
// Define the update parameters
UpdateItemRequest request = UpdateItemRequest.builder()
.tableName(tableName)
.key(key)
.updateExpression("SET #setAttr = :setValue")
.expressionAttributeNames(Map.of("#setAttr", setAttributeName))
.expressionAttributeValues(Map.of(":setValue", setValue))
.returnValues(ReturnValue.UPDATED_NEW)
.build();
// Perform the update operation
return dynamoDbClient.updateItem(request);
}
/**
* Gets the current value of a set attribute.
*
* Helper method to retrieve the current value of a set attribute.
*
* @param dynamoDbClient The DynamoDB client
* @param tableName The name of the DynamoDB table
* @param key The key of the item to get
* @param setAttributeName The name of the set attribute
* @return The set attribute value or null if not found
* @throws DynamoDbException if an error occurs during the operation
*/
public static AttributeValue getSetAttribute(
DynamoDbClient dynamoDbClient, String tableName, Map key, String setAttributeName) {
// Define the get parameters
GetItemRequest request = GetItemRequest.builder()
.tableName(tableName)
.key(key)
.projectionExpression(setAttributeName)
.build();
try {
// Perform the get operation
GetItemResponse response = dynamoDbClient.getItem(request);
// Return the set attribute if it exists, otherwise null
if (response.item() != null && response.item().containsKey(setAttributeName)) {
return response.item().get(setAttributeName);
}
return null;
} catch (DynamoDbException e) {
throw DynamoDbException.builder()
.message("Failed to get set attribute: " + e.getMessage())
.cause(e)
.build();
}
}
```
Example usage of set operations with AWS SDK for Java 2.x.
```
public static void exampleUsage(DynamoDbClient dynamoDbClient, String tableName) {
// Example key
Map key = new HashMap<>();
key.put("ProductId", AttributeValue.builder().s("P12345").build());
System.out.println("Demonstrating set operations in DynamoDB");
try {
// Example 1: Create a string set with multiple values
System.out.println("\nExample 1: Creating a string set with multiple values");
Set