/* * Copyright (c) 1997, 2003, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.lang.ref; /** * Weak reference objects, which do not prevent their referents from being * made finalizable, finalized, and then reclaimed. Weak references are most * often used to implement canonicalizing mappings. * *

Suppose that the garbage collector determines at a certain point in time * that an object is weakly * reachable. At that time it will atomically clear all weak references to * that object and all weak references to any other weakly-reachable objects * from which that object is reachable through a chain of strong and soft * references. At the same time it will declare all of the formerly * weakly-reachable objects to be finalizable. At the same time or at some * later time it will enqueue those newly-cleared weak references that are * registered with reference queues. * * @author Mark Reinhold * @since 1.2 */ public class WeakReference extends Reference { /** * Creates a new weak reference that refers to the given object. The new * reference is not registered with any queue. * * @param referent object the new weak reference will refer to */ public WeakReference(T referent) { super(referent); } /** * Creates a new weak reference that refers to the given object and is * registered with the given queue. * * @param referent object the new weak reference will refer to * @param q the queue with which the reference is to be registered, * or null if registration is not required */ public WeakReference(T referent, ReferenceQueue q) { super(referent, q); } }