Rx Java Observable执行直到某些情况 [英] Rx Java Observable execute until some condition

问题描述

我试图找到一种在满足某些条件之前可以执行观察的方法.

I am trying to find a way to execute observable until some condition is met.

请考虑以下示例:

 myDelayedObservable = createListenerObserver();
    public Observable<Boolean> createListenerObserver() {

      // The part I am looking for
    }

    ViewTreeObserver.OnGlobalLayoutListener listenerLayout = new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
           myDelayedObservable.onCompleted();
         getTargetView().getViewTreeObserver().removeGlobalOnLayoutListener(this);

        }
    };

    public void performMultipleRequests() {

        Observable<Boolean> longRunningTask = Observable.zip(oneRequest, anotherRequest, myDelayedObservable,...);

    }

因此，想法是运行多个请求(例如下载请求)以及使用zip的myDelayedObservable，因此，仅当所有请求和侦听器(在我的情况下为完成的布局)完成时，longRunningTask才完成.

So the idea is to run multiple requests, for instance a download request, together with myDelayedObservable using zip, so longRunningTask completes only when all requests plus listener (in my case view finished layout) are completed.

但是问题是，我找不到为侦听器创建Observable的正确方法.就像障碍一样，伪代码

But the problem is, I cannot find the right way to create my Observable for listener. It is like a barrier, so pseudo code

while(!viewIsLaidOut) {
  // just wait
}
observable.complete();
// After that `longRunningTask` should be completed

请提出实现此目标的正确方法，我已经考虑过Future，Callable，但这似乎并不是我的最佳解决方案.

Please suggest the right way to achieve this, I have thought about Future, Callable but this seems to not be the best solution to me.

推荐答案

1)您需要map所有可观测值都具有相同的类型，例如. Observable<Boolean>，因此您可以将它们合并:

1) You need to map all observables to the same type, eg. Observable<Boolean>, so you can merge them:

observable1.map(String s -> "...".equals(s))
observable2.map(Integer i -> i > 0 && i < 100)
observable3.map(MyClass m -> true)
...

2)使用Observable.merge()将它们全部合并为单个流. 为此目的使用zip仅在所有可观察物发出相同数量的项目时才有效，否则它将在第一个完成后立即完成，而无需等待其余的时间.

2) Use Observable.merge() to merge them all into single stream. Using zip for this purpose will only work if all observables emit the same number of items, otherwise it will complete as soon as the first one completes, without waiting for the rest.

Observable<Boolean> allInOne = Observable.merge(observable1, observable2, ...);

3)myDelayedObservable只是在某些侦听器回叫之前保持allInOne不完整的那些可观察对象之一.为此使用Subject:

3) myDelayedObservable is just one of those observables that shall hold allInOne incomplete until some listener calls back. Use Subject for this purpose:

Subject<Boolean> myDelayedObservable = PublishSubject.create();

4)听众准备就绪后，呼叫myDelayedObservable.onComplete().

4) When your listener is ready, call myDelayedObservable.onComplete().

5)订阅allInOne并在完成时做出反应:

5) Subscribe to allInOne and react on completion:

allInOne.subscribe(b -> { ... }, e -> { ... },
    () -> { ... go ahead with your next task ... });

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