Module org.refcodes.observer

Package org.refcodes.observer

Interface Observable<O>

Type Parameters:

O - The observer type (event listener) observing the Observer.

All Known Implementing Classes:

AbstractObservable

public interface Observable<O>

The Observable interface can be implemented by any class which can be observed by Observer instances (proposal) or any listener interface (custom as of your needs). Whenever something interesting happens to the Observable, then the listeners are informed according to the Observable's implementation. Please regard the listener's documentation on the behavior of the actual listener's methods. Extends it with further functionality using the Observers interface.

Method Summary

Modifier and Type	Method	Description
boolean	hasObserver(O aObserver)	Tests whether the given observer (event listener) has been added to this Observable.
boolean	subscribeObserver(O aObserver)	Adds the given observer (event listener).
boolean	unsubscribeObserver(O aObserver)	Removes the observer (event listener).

Method Details

hasObserver

boolean hasObserver(O aObserver)

Tests whether the given observer (event listener) has been added to this Observable.

Parameters:

aObserver - The observer (event listener) for which to test if it has been added.

Returns:

True if the given observer (event listener) has been added already.

subscribeObserver

boolean subscribeObserver(O aObserver)

Adds the given observer (event listener). The observer (event listener) itself acts as the handle which is used when removing the given observer (event listener) later.

Parameters:

aObserver - The observer (event listener) which is to be added to the Observable.

Returns:

True if the observer (event listener) has been added successfully. If the observer (event listener) has already been added, false is returned.

unsubscribeObserver

boolean unsubscribeObserver(O aObserver)

Removes the observer (event listener). In case the observer (event listener) has not been added before, then false is returned.

Parameters:

aObserver - The observer (event listener) which is to be removed.

Returns:

True if the observer (event listener) has been removed successfully. If there was none such observer (event listener) or if the observer (event listener) has already been removed, then false is returned.