flatMapAndConcatMapCompare.java

@Test
public void flatMapAndConcatMapCompare() throws Exception {
    final List<String> items = Lists.newArrayList("a", "b", "c", "d", "e", "f");

    final TestScheduler scheduler1 = new TestScheduler();
    final TestScheduler scheduler2 = new TestScheduler();

    Observable.from(items)
            .flatMap(s -> Observable.just(s + "x")
                    .delay(5, TimeUnit.SECONDS, scheduler1)
                    .doOnNext(str -> System.out.print(scheduler1.now() + " ")))
            .toList()
            .doOnNext(strings -> System.out.println("\nEND:" + scheduler1.now()))
            .subscribe();

    scheduler1.advanceTimeBy(1, TimeUnit.MINUTES);

    Observable.from(items)
            .concatMap(s -> Observable.just(s + "x")
                    .delay(5, TimeUnit.SECONDS, scheduler2)
                    .doOnNext(str -> System.out.print(scheduler2.now() + " ")))
            .toList()
            .doOnNext(strings -> System.out.println("\nEND:" + scheduler2.now()))
            .subscribe();

    scheduler2.advanceTimeBy(1, TimeUnit.MINUTES);

}