javafx.beans

Class WeakInvalidationListener

java.lang.Object

javafx.beans.WeakInvalidationListener

All Implemented Interfaces:

InvalidationListener, WeakListener

public final class WeakInvalidationListener
extends java.lang.Object
implements InvalidationListener, WeakListener

A WeakInvalidationListener can be used if an Observable should only maintain a weak reference to the listener. This helps to avoid memory leaks that can occur if observers are not unregistered from observed objects after use.

A WeakInvalidationListener is created by passing in the original InvalidationListener. The WeakInvalidationListener should then be registered to listen for changes of the observed object.

Note: You have to keep a reference to the InvalidationListener that was passed in as long as it is in use, otherwise it can be garbage collected too soon.

Since:

JavaFX 2.0

See Also:

InvalidationListener, Observable

Field Summary

Fields

Modifier and Type	Field and Description
private java.lang.ref.WeakReference<InvalidationListener>	ref

Constructor Summary

Constructors

Constructor and Description
WeakInvalidationListener(InvalidationListener listener) The constructor of WeakInvalidationListener.

Method Summary

Modifier and Type	Method and Description
void	invalidated(Observable observable) This method needs to be provided by an implementation of InvalidationListener.
boolean	wasGarbageCollected() Returns true if the linked listener was garbage-collected.

Methods inherited from class java.lang.Object

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

Field Detail

ref

private final java.lang.ref.WeakReference<InvalidationListener> ref

Constructor Detail

WeakInvalidationListener

public WeakInvalidationListener(InvalidationListener listener)

The constructor of WeakInvalidationListener.

Parameters:

listener - The original listener that should be notified

Method Detail

wasGarbageCollected

public boolean wasGarbageCollected()

Returns true if the linked listener was garbage-collected. In this case, the listener can be removed from the observable.

Specified by:

wasGarbageCollected in interface WeakListener

Returns:

true if the linked listener was garbage-collected.

invalidated

public void invalidated(Observable observable)

This method needs to be provided by an implementation of InvalidationListener. It is called if an Observable becomes invalid.

In general, it is considered bad practice to modify the observed value in this method.

Specified by:

invalidated in interface InvalidationListener

Parameters:

observable - The Observable that became invalid