Reuse subscriber

问题:

In RxJava I have a Subscriber object wich I subscribe on a Observable. Later on (some time after onComplete() has been invoked) I create a new Observable and subscribe with the same Subscriber instance used before. However, that seems not work. Is a subscriber not reusable?

Example:

class Loader extends Subscriber<T> {

   public void load(){
       Observable.just("Foo").subscribe(this);
   }

   public void onComplete(){
     // update UI
   }

}

In my code I would like to instantiate a Loader once, and call load() multiple time, for instance after the user clicks on a refresh button ...

回答1:

You cannot reuse Subscriber, because it implements Subscription, which has an isUnsubscribed field which, once set to true, will never become false again, so Subscription is not reusable.

Observer, on the other hand, does not contain any information about the subscription status, so you can reuse it. Each time you subscribe an Observer to an Observable, the RxJava implementation will wrap it inside a new Subscriber for you.

回答2:

Use Observable::concat to create an Observable that emits the items from several Observables in sequence. Subscribe that.