on
Subscribes the given event observer
to receive the events of the given
eventClass
. The order in which notifications will be delivered to the registered listeners is not specified. The method does nothing if the given observer
has been already registered.
Return
a Subscription
reference with which the subscribers can unsubscribe from the Observable
. If the given observer is already registered, returns a reference to already created Subscription
.
Parameters
event Class
the event class
observer
the event observer to subscribe
<E>
the event type