How to stop and resume Observable.interval emiting ticks

Some time ago, I was also looking for kind of RX "timer" solutions, but non of them met my expectations. So there you can find my own solution:

AtomicLong elapsedTime = new AtomicLong();
AtomicBoolean resumed = new AtomicBoolean();
AtomicBoolean stopped = new AtomicBoolean();

public Flowable<Long> startTimer() { //Create and starts timper
    resumed.set(true);
    stopped.set(false);
    return Flowable.interval(1, TimeUnit.SECONDS)
            .takeWhile(tick -> !stopped.get())
            .filter(tick -> resumed.get())
            .map(tick -> elapsedTime.addAndGet(1000));
}

public void pauseTimer() {
    resumed.set(false);
}

public void resumeTimer() {
    resumed.set(true);
}

public void stopTimer() {
    stopped.set(true);
}

public void addToTimer(int seconds) {
    elapsedTime.addAndGet(seconds * 1000);
}

Here's one possible solution:

class TickHandler {

    private AtomicLong lastTick = new AtomicLong(0L);
    private Subscription subscription;

    void resume() {
        System.out.println("resumed");
        subscription = Observable.interval(5, TimeUnit.SECONDS, Schedulers.io())
                                 .map(tick -> lastTick.getAndIncrement())
                                 .subscribe(tick -> System.out.println("tick = " + tick));
    }

    void stop() {
        if (subscription != null && !subscription.isUnsubscribed()) {
            System.out.println("stopped");
            subscription.unsubscribe();
        }
    }
}