为什么不调用doOnDispose？

Question

When creating an Observable like this:

public void foo() {

    Observable observable = Observable.fromCallable(() -> {
        bar();
        return "";
      })
      .doOnSubscribe(disposable -> System.out.println("onSubscribe"))
      .doOnDispose(() -> System.out.println("onDispose"));

    Disposable disposable = observable.subscribe();
    disposable.dispose();    
}

private void bar() {
    System.out.println("bar");
}

doOnSubcribe is called, doOnDispose is not called.

Why is that?

Answer 1

You need to use the doFinally() operator.

doOnDispose() has a very narrow use case, where the observable is explicitly disposed. In your example, the observable terminates "naturally" by onComplete() . By the time that you call dispose() , the observable is done, and nothing will happen -- disposing a completed observable has no effect.