Class WeakReference<T>

Known Direct Subclasses:

public class WeakReference<T>
extends Reference<T>

A weak reference will be cleared, if the object is only weakly reachable. It is useful for lookup tables, where you aren't interested in an entry, if the key isn't reachable anymore. WeakHashtable is a complete implementation of such a table.
It is also useful to make objects unique: You create a set of weak references to those objects, and when you create a new object you look in this set, if the object already exists and return it. If an object is not referenced anymore, the reference will automatically cleared, and you may remove it from the set.
See Also:

Constructor Summary

WeakReference(T referent)
Create a new weak reference, that is not registered to any queue.
WeakReference(T referent, T> q)
Create a new weak reference.

Method Summary

Methods inherited from class java.lang.ref.Reference<T>

clear, enqueue, get, isEnqueued

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details


public WeakReference(T referent)
Create a new weak reference, that is not registered to any queue.
referent - the object we refer to.


public WeakReference(T referent,
                     T> q)
Create a new weak reference.
referent - the object we refer to.
q - the reference queue to register on.
NullPointerException - if q is null.

java.lang.ref.WeakReference Copyright (C) 1999, 2004 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.