Conditional Update in DynamoDB Using Java (Guide w/ Code Examples)

Add a ConditionExpression to UpdateItem to change an item only while its current state matches your expectation. A failed condition raises ConditionalCheckFailedException and leaves the item unchanged.

This example uses Java 17+ and the software.amazon.awssdk:dynamodb SDK 2.x dependency. Configure an AWS Region and credentials through your usual AWS profile or runtime role. The Orders table has String keys pk and sk; adapt the table and keys to your schema.

import java.util.*;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.*;

public class Example {
    static AttributeValue s(String value) { return AttributeValue.builder().s(value).build(); }
    static Map<String, AttributeValue> key(String order) {
        return Map.of("pk", s("CUSTOMER#123"), "sk", s(order));
    }

    public static void main(String[] args) throws InterruptedException {
        try (DynamoDbClient ddb = DynamoDbClient.create()) {
            UpdateItemResponse response = ddb.updateItem(UpdateItemRequest.builder()
                .tableName("Orders").key(key("ORDER#001"))
                .updateExpression("SET #status = :next")
                .conditionExpression("#status = :expected")
                .expressionAttributeNames(Map.of("#status", "status"))
                .expressionAttributeValues(Map.of(":next", s("SHIPPED"), ":expected", s("PENDING")))
                .returnValues(ReturnValue.ALL_NEW).build());
            System.out.println(response.attributes());
        }
    }
}

A condition failure is a business conflict, not a transient error to retry blindly. Reload the item and decide whether the transition is still valid.

Reference: AWS UpdateItem API. For related access patterns, see DynamoDB query examples.