CODEWITHSUNDEEP
kotlinrx-java2
elementstyle
elementstyle

Reputation: 1041

RxJava flatMap with toList

can somebody explain me how to pass onComplete signal over flatMap operator in RxJava?

If flatMap operator is commented I can get list of numbers from 1 to 10 it means toList will receive onComplete signal. But when I want to process data further in flatMap it will consume onComplete signal and I can't get any result. What can I do to pass onComplete signal over flatMap operator?

I have following simple program:

fun main(args: Array<String>) {
    notify()
            .flatMapMaybe { processData(it) }
            .toList()
            .subscribe(
                    { println("onNext: $it") },
                    { println("onError: ${it.message}") }
            )
}

fun notify(): Flowable<Int> {
    return Flowable.create({ emitter ->
        val random = Random()
        for (index in 1..10) {
            emitter.onNext(index)
            Thread.sleep((random.nextInt(500)).toLong())
        }
        emitter.onComplete()

    }, BackpressureStrategy.BUFFER)
}

fun processData(data: Int): Maybe<String> {
    return Maybe.fromCallable { data }
            .flatMap {
                if (it.mod(2) == 0) {
                    Maybe.fromCallable { it.toString() }
                } else {
                    Maybe.never()
                }
            }
}

Upvotes: 1

Views: 232

Answers (1)

ConstOrVar
ConstOrVar

Reputation: 2085

Instead of returning Maybe.never() use Maybe.empty(). According to documentation, Maybe.empty() should post onComplete() immediately.

Upvotes: 2

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