RxJava "groupBy" Operator

output.txt

odd: 1
even: 2
odd: 3
even: 4
odd: 5

RxGroupBy.java

Observable.just(1, 2, 3, 4, 5)
        .groupBy(i -> i % 2 == 0 ? "even" : "odd")
        .subscribe(obs -> {
            if (obs.getKey().equals("even")) {
                obs.subscribe(i -> System.out.println("even: " + i));
            } else {
                obs.subscribe(i -> System.out.println("odd: " + i));
            }
        });