1. /*

  2.  * @(#)FocusListener.java	1.12 00/02/02

  3.  *

  4.  * Copyright 1996-2000 Sun Microsystems, Inc. All Rights Reserved.

  5.  * 

  6.  * This software is the proprietary information of Sun Microsystems, Inc.  

  7.  * Use is subject to license terms.

  8.  * 

  9.  */

  10. 

  11. package java.awt.event;

  12. 

  13. import java.util.EventListener;

  14. 

  15. /**

  16.  * The listener interface for receiving keyboard focus events on 

  17.  * a component.

  18.  * The class that is interested in processing a focus event

  19.  * either implements this interface (and all the methods it

  20.  * contains) or extends the abstract <code>FocusAdapter</code> class

  21.  * (overriding only the methods of interest).

  22.  * The listener object created from that class is then registered with a

  23.  * component using the component's <code>addFocusListener</code> 

  24.  * method. When the component gains or loses the keyboard focus,

  25.  * the relevant method in the listener object 

  26.  * is invoked, and the <code>FocusEvent</code> is passed to it.

  27.  *

  28.  * @see FocusAdapter

  29.  * @see FocusEvent

  30.  * @see <a href="http://java.sun.com/docs/books/tutorial/post1.0/ui/focuslistener.html">Tutorial: Writing a Focus Listener</a>

  31.  * @see <a href="http://www.awl.com/cp/javaseries/jcl1_2.html">Reference: The Java Class Libraries (update file)</a>

  32.  *

  33.  * @author Carl Quinn

  34.  * @version 1.12 02/02/00

  35.  * @since 1.1

  36.  */

  37. public interface FocusListener extends EventListener {

  38. 

  39.     /**

  40.      * Invoked when a component gains the keyboard focus.

  41.      */

  42.     public void focusGained(FocusEvent e);

  43. 

  44.     /**

  45.      * Invoked when a component loses the keyboard focus.

  46.      */

  47.     public void focusLost(FocusEvent e);

  48. }