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
26package 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
48public 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