class MergeAndConcat {

​

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

        Observable<String> src1 = Observable.interval(1, TimeUnit.SECONDS).map(e -> "src1 : "+e);

        Observable<String> src2 = Observable.interval(1, TimeUnit.SECONDS).map(e -> "src2 : "+e);

        src1.concatWith(src2)

        .subscribe(e -> System.out.println("Received : "+ e));

        Thread.sleep(20000);

​

    }

​

}

​