1 /*
2 * Copyright 2000-2004 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * 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.util;
27
28 /**
29 * An abstract wrapper class for an {@code EventListener} class
30 * which associates a set of additional parameters with the listener.
31 * Subclasses must provide the storage and accessor methods
32 * for the additional arguments or parameters.
33 * <p>
34 * For example, a bean which supports named properties
35 * would have a two argument method signature for adding
36 * a {@code PropertyChangeListener} for a property:
37 * <pre>
38 * public void addPropertyChangeListener(String propertyName,
39 * PropertyChangeListener listener)
40 * </pre>
41 * If the bean also implemented the zero argument get listener method:
42 * <pre>
43 * public PropertyChangeListener[] getPropertyChangeListeners()
44 * </pre>
45 * then the array may contain inner {@code PropertyChangeListeners}
46 * which are also {@code PropertyChangeListenerProxy} objects.
47 * <p>
48 * If the calling method is interested in retrieving the named property
49 * then it would have to test the element to see if it is a proxy class.
50 *
51 * @since 1.4
52 */
53 public abstract class EventListenerProxy<T extends EventListener>
54 implements EventListener {
55
56 private final T listener;
57
58 /**
59 * Creates a proxy for the specified listener.
60 *
61 * @param listener the listener object
62 */
63 public EventListenerProxy(T listener) {
64 this.listener = listener;
65 }
66
67 /**
68 * Returns the listener associated with the proxy.
69 *
70 * @return the listener associated with the proxy
71 */
72 public T getListener() {
73 return this.listener;
74 }
75 }
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