MergeObservable.java

        Observable<String> alphabets1 = Observable
                .interval(1, TimeUnit.SECONDS).map(id -> "A" + id);

        Observable<String> alphabets2 = Observable
                .interval(1, TimeUnit.SECONDS).map(id -> "B" + id);

        Observable.merge(alphabets1, alphabets2)
                .subscribe(new Observer<String>() {
                        @Override
                        public void onSubscribe(Disposable d) {

                        }

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

                        @Override
                        public void onError(Throwable e) {

                        }

                        @Override
                        public void onComplete() {

                        }
                    });



        Thread.sleep(5000);