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public final class WeakChangeListener<T> extends java.lang.Object implements ChangeListener<T>
WeakChangeListener
can be used, if an ObservableValue
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.
WeakChangeListener
are created by passing in the original
ChangeListener
. The WeakChangeListener
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 will be garbage collected
to soon.
ChangeListener
,
ObservableValue
Constructor and Description |
---|
WeakChangeListener(ChangeListener<T> listener)
The constructor of
WeakChangeListener . |
Modifier and Type | Method and Description |
---|---|
void |
changed(ObservableValue<? extends T> observable,
T oldValue,
T newValue)
This method needs to be provided by an implementation of
ChangeListener . |
boolean |
wasGarbageCollected()
Returns
true if the linked InvalidationListener was
garbage-collected. |
public WeakChangeListener(ChangeListener<T> listener)
WeakChangeListener
.listener
- The original listener that should be notifiedpublic boolean wasGarbageCollected()
true
if the linked InvalidationListener
was
garbage-collected. In this case, the listener can be removed from the
observable.true
if the linked InvalidationListener
was
garbage-collected.public void changed(ObservableValue<? extends T> observable, T oldValue, T newValue)
ChangeListener
ChangeListener
. It is called if the value of an
ObservableValue
changes.
In general is is considered bad practice to modify the observed value in this method.
changed
in interface ChangeListener<T>
observable
- The ObservableValue
which value changedoldValue
- The old valuenewValue
- The new valueCopyright (c) 2008, 2011, Oracle and/or its affiliates. All rights reserved. Use is subject to