01 /*
02 * Copyright 1997-2003 Sun Microsystems, Inc. All Rights Reserved.
03 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
04 *
05 * This code is free software; you can redistribute it and/or modify it
06 * under the terms of the GNU General Public License version 2 only, as
07 * published by the Free Software Foundation. Sun designates this
08 * particular file as subject to the "Classpath" exception as provided
09 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package java.lang.ref;
27
28 /**
29 * Weak reference objects, which do not prevent their referents from being
30 * made finalizable, finalized, and then reclaimed. Weak references are most
31 * often used to implement canonicalizing mappings.
32 *
33 * <p> Suppose that the garbage collector determines at a certain point in time
34 * that an object is <a href="package-summary.html#reachability">weakly
35 * reachable</a>. At that time it will atomically clear all weak references to
36 * that object and all weak references to any other weakly-reachable objects
37 * from which that object is reachable through a chain of strong and soft
38 * references. At the same time it will declare all of the formerly
39 * weakly-reachable objects to be finalizable. At the same time or at some
40 * later time it will enqueue those newly-cleared weak references that are
41 * registered with reference queues.
42 *
43 * @version 1.25, 05/05/07
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 }
|