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 transferred 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      * @param e the event to be processed
  61      */
  62     public void windowGainedFocus(WindowEvent e);
  63 
  64     /**
  65      * Invoked when the Window is no longer the focused Window, which means
  66      * that keyboard events will no longer be delivered to the Window or any of
  67      * its subcomponents.
  68      * @param e the event to be processed
  69      */
  70     public void windowLostFocus(WindowEvent e);
  71 }