De mest intressanta nyheterna i Java 9 sammanfattade i en Java-klass

Java9Features.java

package se.citerus;

import java.util.Optional;
import java.util.Scanner;
import java.util.concurrent.Flow;
import java.util.concurrent.SubmissionPublisher;
import java.util.stream.IntStream;

public class Java9Features {

    private static class MySubscriber<String> implements Flow.Subscriber<String> {
        private Flow.Subscription subscription;

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

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

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

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

    public static void main(String[] args) {
        IntStream.rangeClosed(0, 10).takeWhile(value -> value <= 5).forEach(System.out::print);
        System.out.println();
        IntStream.rangeClosed(0, 10).dropWhile(value -> value <= 5).forEach(System.out::print);
        System.out.println();

        IntStream.iterate(0, value -> value <= 10, operand -> operand + 2).forEach(System.out::print);
        System.out.println();

        Optional.ofNullable(null).ifPresentOrElse(System.out::println, () -> System.out.println("Nothing to see here"));

        Optional.of("aaa").stream().map(String::length).forEach(System.out::println);

        SubmissionPublisher<String> publisher = new SubmissionPublisher<>();

        MySubscriber<String> subscriber = new MySubscriber<>();
        publisher.subscribe(subscriber);

        Scanner scan = new Scanner(System.in);
        String input;
        do {
            input = scan.next();
            publisher.submit(input);
        } while (!input.contains("quit"));

        subscriber.subscription.cancel();
        publisher.close();
    }
}