Observable creation with unsubscription

Create.java

package com.subinkrishna.rx;

import rx.Observable;
import rx.Subscriber;
import rx.Subscription;
import rx.functions.Action0;
import rx.functions.Action1;
import rx.schedulers.Schedulers;
import rx.subscriptions.Subscriptions;

public class Create {

    public static void main(String[] args) throws Exception {

        System.out.println("Start" + " (" + Thread.currentThread().getId() + ")");

        Observable<String> observe = Observable.create(new Observable.OnSubscribe<String>() {
            @Override
            public void call(Subscriber<? super String> subscriber) {
                System.out.println("Call" + " (" + Thread.currentThread().getId() + ")");
                subscriber.onNext("Hello!");
                // Unsubscribes all the subscriptions!
                // subscriber.onCompleted();
                subscriber.add(Subscriptions.create(new Action0() {
                    @Override
                    public void call() {
                        System.out.println("World!" + " (" + Thread.currentThread().getId() + ")");
                    }
                }));
            }
        });

        Subscription sub = observe
                .subscribeOn(Schedulers.io())
                .observeOn(Schedulers.newThread())
                .doOnNext(new Action1<String>() {
                    @Override
                    public void call(String s) {
                        System.out.println("doOnNext: " + s + " (" + Thread.currentThread().getId() + ")");
                    }
                })
                .subscribe(new Subscriber<String>() {
                    @Override
                    public void onCompleted() {
                        System.out.println("onCompleted" + " (" + Thread.currentThread().getId() + ")");
                    }

                    @Override
                    public void onError(Throwable throwable) {

                    }

                    @Override
                    public void onNext(String s) {
                        System.out.println("onNext: " + s + " (" + Thread.currentThread().getId() + ")");
                    }
                });

        Thread.sleep(2000);
        System.out.println("End" + " (" + Thread.currentThread().getId() + ")");
        sub.unsubscribe();
    }

}