1 /* 2 * Copyright (c) 1996, 2006, 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 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://docs.oracle.com/javase/tutorial/uiswing/events/focuslistener.html">Tutorial: Writing a Focus Listener</a> 46 * 47 * @author Carl Quinn 48 * @since 1.1 49 */ 50 public interface FocusListener extends EventListener { 51 52 /** 53 * Invoked when a component gains the keyboard focus. 54 */ 55 public void focusGained(FocusEvent e); 56 57 /** 58 * Invoked when a component loses the keyboard focus. 59 */ 60 public void focusLost(FocusEvent e); 61 }