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Java > Open Source Codes > org > jfree > ui > JTextObserver


1 /* ========================================================================
2  * JCommon : a free general purpose class library for the Java(tm) platform
3  * ========================================================================
4  *
5  * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
6  *
7  * Project Info: http://www.jfree.org/jcommon/index.html
8  *
9  * This library is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU Lesser General Public License as published by
11  * the Free Software Foundation; either version 2.1 of the License, or
12  * (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17  * License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
22  * USA.
23  *
24  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
25  * in the United States and other countries.]
26  *
27  * ------------------
28  * JTextObserver.java
29  * ------------------
30  * (C) Copyright 2004, by Thomas Morgner and Contributors.
31  *
32  * Original Author: Thomas Morgner;
33  * Contributor(s): David Gilbert (for Object Refinery Limited);
34  *
35  * $Id: JTextObserver.java,v 1.5 2005/10/18 13:18:34 mungady Exp $
36  *
37  * Changes
38  * -------
39  * 07-Jun-2004 : Added JCommon header (DG);
40  *
41  */
42
43 package org.jfree.ui;
44
45 import java.awt.event.FocusEvent JavaDoc;
46 import java.awt.event.FocusListener JavaDoc;
47
48 import javax.swing.text.JTextComponent JavaDoc;
49
50 /**
51  * An observer that selects all the text when a field gains the focus.
52  *
53  * @author Thomas Morgner
54  */
55 public final class JTextObserver implements FocusListener JavaDoc {
56
57     /** The singleton instance. */
58     private static JTextObserver singleton;
59
60     /**
61      * Creates a new instance.
62      */
63     private JTextObserver() {
64         // nothing required
65 }
66
67     /**
68      * Returns the single instance.
69      *
70      * @return The single instance.
71      */
72     public static JTextObserver getInstance() {
73         if (singleton == null) {
74            singleton = new JTextObserver();
75         }
76         return singleton;
77     }
78
79     /**
80      * Selects all the text when a field gains the focus.
81      *
82      * @param e the focus event.
83      */
84     public void focusGained(final FocusEvent JavaDoc e) {
85         if (e.getSource() instanceof JTextComponent JavaDoc) {
86             final JTextComponent JavaDoc tex = (JTextComponent JavaDoc) e.getSource();
87             tex.selectAll();
88         }
89     }
90
91     /**
92      * Deselects the text when a field loses the focus.
93      *
94      * @param e the event.
95      */
96     public void focusLost(final FocusEvent JavaDoc e) {
97         if (e.getSource() instanceof JTextComponent JavaDoc) {
98             final JTextComponent JavaDoc tex = (JTextComponent JavaDoc) e.getSource();
99             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 JavaDoc 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 JavaDoc t) {
121         if (singleton == null) {
122             singleton = new JTextObserver();
123         }
124         t.removeFocusListener(singleton);
125     }
126     
127 }
128
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