RxJava：为多个 Observable 使用相同的 Observer 调用 .subscribe()

Question

What is the behavior of the same Observer calling .subscribe() on several Observables?

Will they be implicitly merged? Or is it that that last on wins?

For instance:

event1.subscribe(myObserver);
event2.subscribe(myObserver);

Answer 1

Based on the javadoc , as long as you don't cancel the Subscription s returned by each Observables, the observer will be subscribed to all observables .

I expect if you subscribe the same observer multiple times to one observable, you will be notified multiple times - otherwise the subscriptions made previously would "magically" go dead, which is something that may cause troubles.

// data members
Observable x, y;

void foo(Subscriber a) {
  // is subscriber a already registered with x?
  // Nevermind, I'm gonna make sure it is!
  Subscription s=x.subscribe(a);
  // provoke a change to be caught by 'a'

  // do some work based on whatever Subscriber 'a' captured.

  s.unsubscribe();
}

void bar() {
  Subscriber m;
  Subscription mx=x.subscribe(m);
  Subscription my=y.subscribe(m);

  // do something and then...
  foo(mx); // one would expect the mx subscription is still valid here!!!
  // do some more work

  my.unsubscribe();
  mx.unsubscribe();
}