MainActivity.java

//Class that combines both data streams
class ZipObject {
    int number; 
    String alphabet;
}

Observable<Integer> observable1 = Observable.from(new Integer[]{1, 2, 3, 4, 5});  //Emits integers
Observable<String> observable2 = Observable.from(new String[]{"A", "B", "C", "D", "F"});  //Emits alphabets
Observable<ZipObject> observable = Observable.zip(observable1, observable2,   
    //Function that define how to zip outputs of both the stream into single object.
    new Func2<Integer, String, ZipObject>() { 
        @Override
        public ZipObject call(Integer integer, String s) {
            ZipObject zipObject = new ZipObject();
            zipObject.alphabet = s;
            zipObject.number = integer;
            return zipObject;
        }
    });

observable
    .subscribeOn(Schedulers.newThread())
    .observeOn(Schedulers.io())
    .subscribe(new Action1<ZipObject>() {
        @Override
        public void call(ZipObject zipObject) {
            Log.d("Observer", "Output:" + zipObject.number + " " + zipObject.alphabet);
        }
    });
}