rxjava_parallelization_example.java

public class JavaLauncher {
    public static void main(String[] args) {
        Observable<Integer> source = Observable.range(1,10);

        source.map(i -> sleep(i, 250))
                .doOnNext(i -> System.out.println("Emitting " + i + " on thread " + Thread.currentThread().getName()))
                .flatMap(i -> 
                    Observable.just(i)
                        .subscribeOn(Schedulers.computation())
                        .map(i2 -> sleep(i2 * 10, 500))
                )
                .subscribe( i -> System.out.println("Received " + i + " on thread " + Thread.currentThread().getName()));

        sleep(-1, 30000);
    }

    private static int sleep(int i, int time) {
        try {
            Thread.sleep(time);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return i;
    }
}

/* OUTPUT
Emitting 1 on thread main
Emitting 2 on thread main
Emitting 3 on thread main
Received 10 on thread RxComputationThreadPool-3
Emitting 4 on thread main
Received 20 on thread RxComputationThreadPool-4
Received 30 on thread RxComputationThreadPool-1
Emitting 5 on thread main
Received 40 on thread RxComputationThreadPool-2
Emitting 6 on thread main
Received 50 on thread RxComputationThreadPool-3
Emitting 7 on thread main
Received 60 on thread RxComputationThreadPool-4
Emitting 8 on thread main
Received 70 on thread RxComputationThreadPool-1
Emitting 9 on thread main
Received 80 on thread RxComputationThreadPool-2
Emitting 10 on thread main
Received 90 on thread RxComputationThreadPool-3
Received 100 on thread RxComputationThreadPool-4
*/