How can PublishSubject and BehaviorSubject be unsubscribed from?

Question

Under the subjects package you have classes like PublishSubject and BehaviorSubject which I suppose can be described as some usable sa

Answer 1

Subjects are essentially are both Observables and Observers.

An Observable is essentially a thing that has a function that takes an Observer and returns a subscription. So, for example, given simple observable:

    Observable observable = Observable.create(new Observable.OnSubscribeFunc() {
        @Override
        public Subscription onSubscribe(Observer observer) {
            observer.onNext(3);
            observer.onNext(2);
            observer.onNext(1);
            observer.onCompleted();

            return Subscriptions.empty();
        }
    });

And here we would subscribe to it, to print out a line for each integer:

    Subscription sub = observable.subscribe(new Action1() {
        @Override
        public void call(Integer integer) {
            System.out.println(integer);
        }
    });

You would unsubscribe on the above by calling sub.unsubscribe().

Here is a PublishSubject that does roughly the same thing:

    PublishSubject publishSubject = PublishSubject.create();
    Subscription subscription = publishSubject.subscribe(new Action1() {
        @Override
        public void call(Integer integer) {
            System.out.println(integer);
        }
    });

    publishSubject.onNext(3);
    publishSubject.onNext(2);
    publishSubject.onNext(1);

You would unsubscribe from it the same way, by calling subscription.unsubscribe().