Java 9 introduces native support for Reactive Streams, which is a specification for asynchronous stream processing with non-blocking back pressure. This is a significant improvement that allows developers to write more efficient and scalable code when dealing with streams of data.

What are Reactive Streams?

Reactive Streams is an initiative to provide a standard for asynchronous stream processing in a non-blocking manner, with the ability to handle back pressure. It aims to enable developers to build systems that can react to and process streams of data efficiently, while avoiding issues such as buffer overflow or exhaustion.

Why Java 9?

Java 9 includes an implementation of the Reactive Streams specification as a part of the Java SE Platform. This means that developers no longer need to rely on external libraries or frameworks to work with Reactive Streams in Java.

How to use Reactive Streams in Java 9

Java 9 introduces the Flow API, which provides classes and interfaces for working with Reactive Streams. Here’s a simple example that demonstrates the basics of Reactive Streams in Java 9:

import java.util.Arrays;
import java.util.concurrent.SubmissionPublisher;
import java.util.concurrent.Flow.*;

public class ReactiveStreamsExample {
    public static void main(String[] args) {
        SubmissionPublisher<String> publisher = new SubmissionPublisher<>();

        Subscriber<String> subscriber = new Subscriber<>() {
            private Subscription subscription;

            @Override
            public void onSubscribe(Subscription subscription) {
                this.subscription = subscription;
                this.subscription.request(1);
            }

            @Override
            public void onNext(String item) {
                System.out.println("Received item: " + item);
                this.subscription.request(1);
            }

            @Override
            public void onError(Throwable throwable) {
                throwable.printStackTrace();
            }

            @Override
            public void onComplete() {
                System.out.println("Processing complete");
            }
        };

        publisher.subscribe(subscriber);

        Arrays.asList("item1", "item2", "item3").forEach(publisher::submit);

        publisher.close();
    }
}

In this example, we create a SubmissionPublisher which acts as the source of the stream. We then create a custom Subscriber implementation to process the stream. The onSubscribe method is called when the subscriber is ready to receive items, and the onNext method is called for each item in the stream. The onError and onComplete methods handle error and completion events respectively.

Finally, we subscribe the Subscriber to the SubmissionPublisher and submit some items to the stream. We close the publisher to indicate the end of the stream.

Conclusion

Java 9’s native support for Reactive Streams brings many benefits to developers in terms of efficiency and scalability when working with streams of data. The Flow API simplifies the implementation of Reactive Streams in Java and allows developers to build more resilient and responsive applications.

To learn more about Reactive Streams in Java, check out the official documentation.

#reactivestreams #java9