Java 11 runtime now available in AWS Lambda

We are excited to announce that you can now develop your AWS Lambda functions using the Java 11 runtime. Start using this runtime today by specifying a runtime parameter value of java11 when creating or updating your Lambda functions.

The Java 11 runtime does not introduce any changes in Lambda’s programming model, such as handler definition or logging statements. Customers can continue authoring their Lambda functions in Java as they have in the past while benefitting from the new features of Java 11.

New features in Java 11 runtime

Java 11 is a long-term support release and brings with it several new features, including a Java-native HTTP client with HTTP/2 support and the var keyword. The Java 11 runtime also benefits from Amazon Corretto running on Amazon Linux 2.

HTTP client (standard)

Java 11 introduces a native HTTP client, HttpClient. Previous versions of Java provided the HttpURLConnection class for accessing HTTP resources but, for more complex use cases, developers typically had to select and import a third-party library. HttpClient supports both synchronous and asynchronous HTTP requests.

Example: Synchronous HTTP request

Synchronous requests block execution while the HTTP client waits for a response. This is a common programming model for Lambda functions that are invoked synchronously themselves, for example, via Amazon API Gateway.

package helloworld;

import java.net.http.HttpClient;
import java.net.http.HttpHeaders;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.net.http.HttpResponse.BodyHandlers;
import java.net.URI;
import java.time.Duration;
import java.util.HashMap;
import java.util.Map;

import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.RequestHandler;

/**
 * Handler for requests to Lambda function.
 */
public class App implements RequestHandler<Object, Object> {

    public Object handleRequest(final Object input, final Context context) {
        Map<String, String> headers = new HashMap<>();
        headers.put("Content-Type", "application/json");
        headers.put("X-Custom-Header", "application/json");
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
            .GET()
            .version(HttpClient.Version.HTTP_2)
            .uri(URI.create("https://checkip.amazonaws.com"))
            .timeout(Duration.ofSeconds(15))
            .build();

        try {
            HttpResponse<String> response =
            client.send(request, BodyHandlers.ofString());

            String output = String.format("{ \"message\": \"hello world\", \"location\": \"%s\" }", response.body());
            return new GatewayResponse(output, headers, response.statusCode());    
        } catch (Exception e) {
            return new GatewayResponse("{}", headers, 500);
        }
    }
}

The var keyword

The var keyword allows you to declare local variables and infer their type at compile time. This helps reduce verbosity, especially with composite types, as you no longer have to explicitly define type information on both sides of the equal sign. For example, to create a map of key/value string pairs, you can now do:

var map = new HashMap<String, String>();

Corretto benefits

The Java 11 runtime benefits from Amazon Corretto. Corretto is a no-cost, multiplatform, production-ready distribution of the Open Java Development Kit (OpenJDK). Corretto comes with long-term support that will include performance enhancements and security fixes. Amazon runs Corretto internally on thousands of production services.

Special considerations

Developers migrating to the new runtimes should consider the following known issues.

Java 8 to Java 11 migration

After migrating from Java 8 to Java 11, using internal packages such as sun.misc.* or sun.* now produces compiler errors instead of warnings.

Amazon Linux 2

Java 11, like Python 3.8 and Node.js 10 and 12, is based on an Amazon Linux 2 execution environment. Amazon Linux 2 provides a secure, stable, and high-performance execution environment to develop and run cloud and enterprise applications.

Next steps

Get started building with Java 11 today by specifying a runtime parameter value of java11 when creating or updating your Lambda functions.

Hope you enjoy building with the new features in Java 11!

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