01 /*
02 * Copyright 1996-2006 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.awt.event;
27
28 import java.util.EventListener;
29
30 /**
31 * The listener interface for receiving keyboard focus events on
32 * a component.
33 * The class that is interested in processing a focus event
34 * either implements this interface (and all the methods it
35 * contains) or extends the abstract <code>FocusAdapter</code> class
36 * (overriding only the methods of interest).
37 * The listener object created from that class is then registered with a
38 * component using the component's <code>addFocusListener</code>
39 * method. When the component gains or loses the keyboard focus,
40 * the relevant method in the listener object
41 * is invoked, and the <code>FocusEvent</code> is passed to it.
42 *
43 * @see FocusAdapter
44 * @see FocusEvent
45 * @see <a href="http://java.sun.com/docs/books/tutorial/post1.0/ui/focuslistener.html">Tutorial: Writing a Focus Listener</a>
46 *
47 * @author Carl Quinn
48 * @version 1.23 05/05/07
49 * @since 1.1
50 */
51 public interface FocusListener extends EventListener {
52
53 /**
54 * Invoked when a component gains the keyboard focus.
55 */
56 public void focusGained(FocusEvent e);
57
58 /**
59 * Invoked when a component loses the keyboard focus.
60 */
61 public void focusLost(FocusEvent e);
62 }
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