org.modeshape.graph.observe
Class ChangeObserver

java.lang.Object
  org.modeshape.graph.observe.ChangeObserver

All Implemented Interfaces:

Observer

Direct Known Subclasses:

NetChangeObserver

@ThreadSafe
public abstract class ChangeObserver
extends Object
implements Observer

Abstract class that is used to signal that a change set has occurred. This class is typically subclassed by those that wish to observe changes in content, and registered with a Observable.

This class maintains a (weak) reference to the ChangeSource instances with which it is registered. Therefore, the observers will not keep a ChangeSource from being garbage collected. And, if a change source is garbage collected, calling unregister() will clean up naturally.

Nested Class Summary

protected class

ChangeObserver.ChangeSourceReference A WeakReference implementation that provides a valid

Constructor Summary

protected

ChangeObserver()

Method Summary

protected void	doUnregister() Method called by unregister() that actually does the unregistering.
boolean	isRegistered() Determine whether this observer is currently registered with any Observable instances.
abstract void	notify(Changes changeSet) Method that is called for each Changes from the Observable instance(s) with which this listener is registered.
void	unregister() Unregister this listener from all sources that it was registered with.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ChangeObserver

protected ChangeObserver()

Method Detail

unregister

public void unregister()

Unregister this listener from all sources that it was registered with. This is preferred over calling Observable.unregister(Observer) directly.

doUnregister

protected final void doUnregister()

Method called by unregister() that actually does the unregistering. This method is final.

isRegistered

public boolean isRegistered()

Determine whether this observer is currently registered with any Observable instances.

Although an observer might be registered with an Observable, if that Observable is garbage collected, then this observer will no longer be registered with it.

Returns:

true if this observer is registered with at least one Observable instance, or false if this observer is not currently registered with any Observable instances.

notify

public abstract void notify(Changes changeSet)

Method that is called for each Changes from the Observable instance(s) with which this listener is registered.

Specified by:

notify in interface Observer

Parameters:

changeSet - the change set