CODEWITHSUNDEEP
kotlinrx-java2
Piotr Aleksander Chmielowski
Piotr Aleksander Chmielowski

Reputation: 6432

Make original Observable complete when the one inside flatMap completes

I have an Observable on which I'm applying the flatMap operator. Is it possible to make this original Observable complete when the second one completes?

Here is the code.

Observable.never<Int>()
        .startWith(0)
        .doOnComplete { println("Completed") } // Not called.
        .flatMap { Observable.fromArray(1, 2, 3, 4, 5) /* Completes after 5 */ }
        .subscribe(::println)

The output is:

1
2
3
4
5

I'm trying to achieve the following output:

1
2
3
4
5
Completed

Upvotes: 2

Views: 55

Answers (1)

Tuby
Tuby

Reputation: 3253

You can make use of operator materialize which will help you get information about what is hapening inside flatMap. Then you can dispose upstream when you receive onComplete notification(by taking only onNext Notifications).

    Observable.<Integer>never()
            .startWith(0)
            .flatMap(integer -> Observable.range(1, 5)
                    .materialize())
            .takeWhile(notification -> notification.isOnNext())
            .map(notification -> notification.getValue())
            .doOnComplete(() -> System.out.println("Completed"))
            .subscribe(integer -> System.out.println(integer));

Result

1
2
3
4
5
Completed

Upvotes: 1

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