Reading dynamo db data using java.

Question

This is code i am using to read data :
public static AmazonDynamoDB initializeDynamoDBClient() {
		// Set your AWS credentials
		String accessKey = "*********************";
		String secretKey = "*******************/SUnL";
		BasicAWSCredentials awsCreds = new BasicAWSCredentials(accessKey, secretKey);
		// Create a DynamoDB client
		AmazonDynamoDB client = AmazonDynamoDBClient.builder().withRegion(Regions.AP_SOUTH_1) 																							 
                     // desired AWS region
				.withCredentials(new AWSStaticCredentialsProvider(awsCreds)).build();
		return client;
	}
	public static void main(String[] args) {
		AmazonDynamoDB dynamoDB = initializeDynamoDBClient();
		System.out.println(dynamoDB.listTables());
		AmazonDynamoDB dynamoDBClient = 
                                                        AmazonDynamoDBClientBuilder.standard().withRegion("AP_SOUTH_1") // 																							
				.build();

DynamoDB dynamo_DB = new DynamoDB(dynamoDBClient);
		// Replace "YourTableName" with the name of your DynamoDB table
		String tableName = "Automation";
		// Get the DynamoDB table
		Table table = dynamo_DB.getTable(tableName);
		// Specify the primary key value you want to retrieve
		String Pk = "MG2GFRP9411";
		// Retrieve the item using its primary key
		//Item item=dynamoDBClient.getItem(null)
		Item item = table.getItem("Automation007", Pk);

if (item != null) {
			// Do something with the retrieved item
			System.out.println("Item: " + item.toJSONPretty());
		} else {
			System.out.println("No matching item found in the table.");
		}
	}

this is output i am getting :

Client Name : com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient@58359ebd
{TableNames: [Automation],}
Dynamo DB Table Name : {Automation: null}
Exception in thread "main" com.amazonaws.SdkClientException: Unable to load AWS credentials from any provider in the chain: [EnvironmentVariableCredentialsProvider: Unable to load AWS credentials from environment variables (AWS_ACCESS_KEY_ID (or AWS_ACCESS_KEY) and AWS_SECRET_KEY (or AWS_SECRET_ACCESS_KEY)), SystemPropertiesCredentialsProvider: Unable to load AWS credentials from Java system properties (aws.accessKeyId and aws.secretKey), WebIdentityTokenCredentialsProvider: To use assume role profiles the aws-java-sdk-sts module must be on the class path., com.amazonaws.auth.profile.ProfileCredentialsProvider@6d91790b: profile file cannot be null, com.amazonaws.auth.EC2ContainerCredentialsProviderWrapper@4a1c0752: Failed to connect to service endpoint: ]
	at com.amazonaws.auth.AWSCredentialsProviderChain.getCredentials(AWSCredentialsProviderChain.java:142)
	at com.amazonaws.http.AmazonHttpClient$RequestExecutor.getCredentialsFromContext(AmazonHttpClient.java:1269)
	at com.amazonaws.http.AmazonHttpClient$RequestExecutor.runBeforeRequestHandlers(AmazonHttpClient.java:845)
	at com.amazonaws.http.AmazonHttpClient$RequestExecutor.doExecute(AmazonHttpClient.java:794)
	at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeWithTimer(AmazonHttpClient.java:781)
	at com.amazonaws.http.AmazonHttpClient$RequestExecutor.execute(AmazonHttpClient.java:755)
	at com.amazonaws.http.AmazonHttpClient$RequestExecutor.access$500(AmazonHttpClient.java:715)
	at com.amazonaws.http.AmazonHttpClient$RequestExecutionBuilderImpl.execute(AmazonHttpClient.java:697)
	at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:561)
	at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:541)
	at com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.doInvoke(AmazonDynamoDBClient.java:6875)
	at com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.invoke(AmazonDynamoDBClient.java:6842)
	at com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.executeGetItem(AmazonDynamoDBClient.java:3493)
	at com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.getItem(AmazonDynamoDBClient.java:3457)
	at com.amazonaws.services.dynamodbv2.document.internal.GetItemImpl.doLoadItem(GetItemImpl.java:77)
	at com.amazonaws.services.dynamodbv2.document.internal.GetItemImpl.getItemOutcome(GetItemImpl.java:40)
	at com.amazonaws.services.dynamodbv2.document.internal.GetItemImpl.getItemOutcome(GetItemImpl.java:99)
	at com.amazonaws.services.dynamodbv2.document.internal.GetItemImpl.getItem(GetItemImpl.java:111)
	at com.amazonaws.services.dynamodbv2.document.Table.getItem(Table.java:624)
	at Get_DynamoDB_Data.main(Get_DynamoDB_Data.java:52)

Mark Bradshaw · Answer

Hi Mr R,
From what I can understand of your code and output, I can see that you have successfully printed out the list of table names that you have as the output before the Exception shows:
```
Client Name : com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient@58359ebd {TableNames: [Automation],} Dynamo DB Table Name : {Automation: null} 
```

This shows your initial DynamoDB client initialization has worked and you have connected to DynamoDB and returned something.
Digging further I can see that under "main" you are then initializing another DynamoDB client:
```
AmazonDynamoDB dynamoDBClient = AmazonDynamoDBClientBuilder
		.standard()
		.withRegion("AP_SOUTH_1")
		.build();
```

This initialization is missing .withCredentials which I believe is causing your exception. You also already have a DynamoDB client initialized in "initializeDynamoDBClient()" so there is no need to initialize a new client. I haven't gone through the rest of your code to check if it works, but to make progress I recommend changing the start of your main function to:
```
public static void main(String[] args) {
	AmazonDynamoDB dynamoDBClient = initializeDynamoDBClient(); 
	System.out.println(dynamoDBClient.listTables());

// Delete unneccessary call to AmazonDynamoDBClientBuilder
	// Continue from here with your getItem query
```

and continue from there.

There's also good documentation on [Querying tables using Java with the DynamoDB SDK](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/example_dynamodb_Scenario_GettingStartedMovies_section.html) that should help you get your code running successfully.

Reading dynamo db data using java.

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