1 /* 2 * Copyright (c) 1997, 2003, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.lang.ref; 27 28 29 /** 30 * Weak reference objects, which do not prevent their referents from being 31 * made finalizable, finalized, and then reclaimed. Weak references are most 32 * often used to implement canonicalizing mappings. 33 * 34 * <p> Suppose that the garbage collector determines at a certain point in time 35 * that an object is <a href="package-summary.html#reachability">weakly 36 * reachable</a>. At that time it will atomically clear all weak references to 37 * that object and all weak references to any other weakly-reachable objects 38 * from which that object is reachable through a chain of strong and soft 39 * references. At the same time it will declare all of the formerly 40 * weakly-reachable objects to be finalizable. At the same time or at some 41 * later time it will enqueue those newly-cleared weak references that are 42 * registered with reference queues. 43 * 44 * @author Mark Reinhold 45 * @since 1.2 46 */ 47 48 public class WeakReference<T> extends Reference<T> { 49 50 /** 51 * Creates a new weak reference that refers to the given object. The new 52 * reference is not registered with any queue. 53 * 54 * @param referent object the new weak reference will refer to 55 */ 56 public WeakReference(T referent) { 57 super(referent); 58 } 59 60 /** 61 * Creates a new weak reference that refers to the given object and is 62 * registered with the given queue. 63 * 64 * @param referent object the new weak reference will refer to 65 * @param q the queue with which the reference is to be registered, 66 * or <tt>null</tt> if registration is not required 67 */ 68 public WeakReference(T referent, ReferenceQueue<? super T> q) { 69 super(referent, q); 70 } 71 72 } 73
