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1   /*
2    * Copyright (c) 2000, 2013, 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.awt.event;
27  
28  import java.util.EventListener;
29  
30  /**
31   * The listener interface for receiving <code>WindowEvents</code>, including
32   * <code>WINDOW_GAINED_FOCUS</code> and <code>WINDOW_LOST_FOCUS</code> events.
33   * The class that is interested in processing a <code>WindowEvent</code>
34   * either implements this interface (and
35   * all the methods it contains) or extends the abstract
36   * <code>WindowAdapter</code> class (overriding only the methods of interest).
37   * The listener object created from that class is then registered with a
38   * <code>Window</code>
39   * using the <code>Window</code>'s <code>addWindowFocusListener</code> method.
40   * When the <code>Window</code>'s
41   * status changes by virtue of it being opened, closed, activated, deactivated,
42   * iconified, or deiconified, or by focus being transfered into or out of the
43   * <code>Window</code>, the relevant method in the listener object is invoked,
44   * and the <code>WindowEvent</code> is passed to it.
45   *
46   * @author David Mendenhall
47   *
48   * @see WindowAdapter
49   * @see WindowEvent
50   * @see <a href="http://docs.oracle.com/javase/tutorial/uiswing/events/windowlistener.html">Tutorial: Writing a Window Listener</a>
51   *
52   * @since 1.4
53   */
54  public interface WindowFocusListener extends EventListener {
55  
56      /**
57       * Invoked when the Window is set to be the focused Window, which means
58       * that the Window, or one of its subcomponents, will receive keyboard
59       * events.
60       */
61      public void windowGainedFocus(WindowEvent e);
62  
63      /**
64       * Invoked when the Window is no longer the focused Window, which means
65       * that keyboard events will no longer be delivered to the Window or any of
66       * its subcomponents.
67       */
68      public void windowLostFocus(WindowEvent e);
69  }