why rxjava Observable.subscribe(observer) return void?

Question

When I'm using Observable.subscribe() normally returns Disposable.

But Observable.subscribe(Observer) returns void.

So I can't dispose to Observable.subscribe(Observer).

According to introtorx.com Observable.subscribe(Obeserver) returns Disposable.

Why are rx and rxjava different?

++++++++++++++

I use compile 'io.reactivex.rxjava2:rxandroid:2.0.1' in Android Studio.

github.com/ReactiveX/RxJava/blob/2.x/src/main/java/io/reactivex/Observable.java#L10831

public final void subscribe(Observer<? super T> observer) {
  ... 
}

[[1]: https://i.stack.imgur.com/0owg1.png][1]

[[2]: https://i.stack.imgur.com/7H4av.jpg][2]

Answer 1

It's probably because of the Reactive Stream contract.

Reactive Stream README

public interface Publisher<T> {
    public void subscribe(Subscriber<? super T> s);
}

The interface of Publisher is defined return void. RxJava Flowable implements that interface. And RxJava Observable follow that contract as well.

So they provide a subscribeWith() to return you a Disposable instead of void. Or you can use those overload method which can give you back a disposable too ex: subscribe(consumer<T>,consumer<Throwable>,action)

PS: above its my guess. I'm not sure of it.

Answer 2

In RxJava2, Disposable object is passed to Observer's onSubscribe call back method. You can get hold of Disposable object from onSubscribe call back method and use it to dispose the subscription at later point of time after subscribing the observer to observable.