001 /* ========================================================================
002 * JCommon : a free general purpose class library for the Java(tm) platform
003 * ========================================================================
004 *
005 * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
006 *
007 * Project Info: http://www.jfree.org/jcommon/index.html
008 *
009 * This library is free software; you can redistribute it and/or modify it
010 * under the terms of the GNU Lesser General Public License as published by
011 * the Free Software Foundation; either version 2.1 of the License, or
012 * (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but
015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
017 * License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this library; if not, write to the Free Software
021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
022 * USA.
023 *
024 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
025 * in the United States and other countries.]
026 *
027 * ------------------
028 * JTextObserver.java
029 * ------------------
030 * (C) Copyright 2004, by Thomas Morgner and Contributors.
031 *
032 * Original Author: Thomas Morgner;
033 * Contributor(s): David Gilbert (for Object Refinery Limited);
034 *
035 * $Id: JTextObserver.java,v 1.5 2005/10/18 13:18:34 mungady Exp $
036 *
037 * Changes
038 * -------
039 * 07-Jun-2004 : Added JCommon header (DG);
040 *
041 */
042
043 package org.jfree.ui;
044
045 import java.awt.event.FocusEvent;
046 import java.awt.event.FocusListener;
047
048 import javax.swing.text.JTextComponent;
049
050 /**
051 * An observer that selects all the text when a field gains the focus.
052 *
053 * @author Thomas Morgner
054 */
055 public final class JTextObserver implements FocusListener {
056
057 /** The singleton instance. */
058 private static JTextObserver singleton;
059
060 /**
061 * Creates a new instance.
062 */
063 private JTextObserver() {
064 // nothing required
065 }
066
067 /**
068 * Returns the single instance.
069 *
070 * @return The single instance.
071 */
072 public static JTextObserver getInstance() {
073 if (singleton == null) {
074 singleton = new JTextObserver();
075 }
076 return singleton;
077 }
078
079 /**
080 * Selects all the text when a field gains the focus.
081 *
082 * @param e the focus event.
083 */
084 public void focusGained(final FocusEvent e) {
085 if (e.getSource() instanceof JTextComponent) {
086 final JTextComponent tex = (JTextComponent) e.getSource();
087 tex.selectAll();
088 }
089 }
090
091 /**
092 * Deselects the text when a field loses the focus.
093 *
094 * @param e the event.
095 */
096 public void focusLost(final FocusEvent e) {
097 if (e.getSource() instanceof JTextComponent) {
098 final JTextComponent tex = (JTextComponent) e.getSource();
099 tex.select(0, 0);
100 }
101 }
102
103 /**
104 * Adds this instance as a listener for the specified text component.
105 *
106 * @param t the text component.
107 */
108 public static void addTextComponent(final JTextComponent t) {
109 if (singleton == null) {
110 singleton = new JTextObserver();
111 }
112 t.addFocusListener(singleton);
113 }
114
115 /**
116 * Removes this instance as a listener for the specified text component.
117 *
118 * @param t the text component.
119 */
120 public static void removeTextComponent(final JTextComponent t) {
121 if (singleton == null) {
122 singleton = new JTextObserver();
123 }
124 t.removeFocusListener(singleton);
125 }
126
127 }