Zipping

Zipping allows you to take an emission from each Observable source and combine it into a single emission. Each Observable can emit a different type, but you can combine these different emitted types into a single emission. Here is an example, If we have an Observable<String> and an Observable<Integer>, we can zip each String and Integer together in a one-to-one pairing and concatenate it with a lambda:

import io.reactivex.Observable;

public class Launcher {
    public static void main(String[] args) {

        Observable<String> source1 =
                Observable.just("Alpha", "Beta", "Gamma", "Delta", "Epsilon");

        Observable<Integer> source2 = Observable.range(1,6);

        Observable.zip(source1, source2, (s,i) -> s + "-" + i)
                .subscribe(System.out::println);
    }
...