Rxjava, how to design an Observable that has to wait for another Observable

2
votes

I'm building an Android app, and new to Rxjava, having a beginner's question: I have an Observable that should emit something straightaway if a condition is met. Otherwise, it has to pause, then trigger another Observable, and wait for that second Observable to emit the second thing. Once the second thing is emitted, it (the first Obserable) should continue and emit its object.

Should the 2nd Observable be placed inside 'call' function of the 1st Observable?

If this question sounds vague, pardon me since I'm not even sure how to design the code.

2
androidrx-java

2 Answers

1
votes

What are these observables you try to 'trigger' and 'pause'? If I understand your problem correctly, you could do something like this (instead of creating an Observable from scratch):

Observable<Integer> first = Observable.just(1, 2, 3);
Observable<Integer> second = Observable.just(4);

Observable<T> toRun;

if (condition) {
    toRun = first;
} else {
    toRun = second.concatWith(first);
}

toRun.toBlocking().forEach(System.out::println);