Delay specific values

Question

I have a motionSensor, which offers me a Subject with a boolean value. true, when movement was detected and false when the sensor doesn't detect anything after a fixed, non-changeable timerange.

I want to turn lights on movement, but the lights should stay on for a given period. false should be delayed.

If a true-value was emitted, while the delay is "delaying", then nothing should happen (aka the lights should stay on).

Consider this table

time t	emitted value	action
1	true	turn lights on
2	false	do nothing
3	none emitted	turn lights off
4	true	turn lights on
5	false	do nothing
6	true	do nothing

Here is some pseudo-code:

motionSensor.isMoving$()
    // delayWhen-method does not exsit
    .delayWhen(Duration.of(5, MINUTES), isMoving -> !isMoving)
    .distinctUntilChanged()
    .subscribe(isMoving -> {
        if (isMoving) {
            turnLightsOn();
        } else {
            turnLightsOff();
        });

I need it in this Github Project

Answer 1

I found no operator, so I wrote it as a manual style.

Subject<Boolean> isMoving$ = getSubject();

isMoving$
    .switchMap(value -> isMoving 
        ? Observable.just(isMoving) 
        : Observable.just(isMoving).delay(5, TimeUnit.MINUTES))
    .distinctUntilChanged()
    .subscribe(isMoving -> isMoving ? turnLightsOn() : turnLightsOff());

Special note: IntelliJ is confused by this code. If it warns you, you can ignore it.