[英]RxJava: Dynamic set of observables
我有一個中央班級,叫做Central
。 它可以添加1-N個可觀察物。 這些我需要動態添加,然后知道何時執行最后的onComplete()。
這個怎么做?
代碼示例:
public class Central {
public void addObservable(Observable o){
// Add the new observable to subscriptions
}
}
更新。
我已經花了一段時間了。 使用@DaveMoten的答案,我已經接近了。
這是我的方法,可隨意添加一個新的Observable,並在所有這些Observable完成時得到通知(偽代碼):
class central {
PublishSubject<Observable<T>> subject = PublishSubject.create();
int commandCount = 0;
int concatCount = 0;
addObservable(Observable newObs){
commandCount++;
concatCount++;
subject.concatMap(o ->
o.doOnCompleted(
() -> {
concatCount--;
LOG.warn("inner completed, concatCount: " + concatCount);
})
).doOnNext(System.out::println)
.doOnCompleted(() -> {
System.out.println("OUTER completed");
} ) .subscribe();
onNext(newObs);
subject.onCompleted(); // If this is here, it ends prematurely (after first onComplete)
// if its not, OUTER onComplete never happens
newObs.subscribe((e) ->{},
(error) -> {},
() -> {
commandCount--;
LOG.warn("inner end: commandCount: " + commandCount);
});
}
}
// ... somewhere else in the app:
Observable ob1 = Observable.just(t1);
addObservable.addObservable(ob1);
// ... and possibly somewhere else:
Observable ob2 = Observable.just(t2, t3);
addObservable(ob2);
// Now, possibly somewhere else:
ob1.onNext(1);
// Another place:
ob2.onNext(2);
日志記錄如下所示:
19:51:16.248 [main] WARN execute: commandCount: 1
19:51:17.340 [main] WARN execute: commandCount: 2
19:51:23.290 [main] WARN execute: commandCount: 3
9:51:26.969 [main] WARN inner completed, concatCount: 2
19:51:27.004 [main] WARN inner end: commandCount: 2
19:51:27.008 [main] WARN inner completed, concatCount: 1
19:51:27.009 [main] WARN inner end: commandCount: 1
19:51:51.745 [ProcessIoCompletion0] WARN inner completed, concatCount: 0
19:51:51.750 [ProcessIoCompletion0] WARN inner completed, concatCount: -1
19:51:51.751 [ProcessIoCompletion0] WARN inner end: commandCount: 0
19:51:51.752 [ProcessIoCompletion0] WARN inner completed, concatCount: -2
19:51:51.753 [ProcessIoCompletion0] WARN inner completed, concatCount: -3
更新:我添加了一些計數器,這些計數器表明我不了解concatMap發生了什么。 您可以看到觀察者本身的lambda訂閱數正確地遞減為0,但是concatMap oncomplete降至-3! 而且OUTER完全不會發生。
使用PublishSubject
:
PublishSubject<Observable<T>> subject =
PublishSubject.create();
subject
// protect against concurrent calls to subject (optional)
.serialize()
.concatMap(o ->
o.doOnCompleted(() -> System.out.println("inner completed")))
.doOnNext(System.out::println)
.doOnCompleted(() -> System.out.println("completed"))
.subscribe(subscriber);
subject.onNext(Observable.just(t1));
subject.onNext(Observable.just(t2, t3));
subject.onCompleted();
.
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