Source for 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 1.6 2007/11/02 17:50:36 taqua 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;
  46: import java.awt.event.FocusListener;
  47: import javax.swing.text.JTextComponent;
  48: 
  49: /**
  50:  * An observer that selects all the text when a field gains the focus.
  51:  *
  52:  * @author Thomas Morgner
  53:  */
  54: public final class JTextObserver implements FocusListener {
  55: 
  56:     /** The singleton instance. */
  57:     private static JTextObserver singleton;
  58: 
  59:     /**
  60:      * Creates a new instance.
  61:      */
  62:     private JTextObserver() {
  63:         // nothing required
  64:     }
  65: 
  66:     /**
  67:      * Returns the single instance.
  68:      * 
  69:      * @return The single instance.
  70:      */
  71:     public static JTextObserver getInstance() {
  72:         if (singleton == null) {
  73:            singleton = new JTextObserver();
  74:         }
  75:         return singleton;
  76:     }
  77: 
  78:     /**
  79:      * Selects all the text when a field gains the focus.
  80:      * 
  81:      * @param e  the focus event.
  82:      */
  83:     public void focusGained(final FocusEvent e) {
  84:         if (e.getSource() instanceof JTextComponent) {
  85:             final JTextComponent tex = (JTextComponent) e.getSource();
  86:             tex.selectAll();
  87:         }
  88:     }
  89: 
  90:     /**
  91:      * Deselects the text when a field loses the focus.
  92:      * 
  93:      * @param e  the event.
  94:      */
  95:     public void focusLost(final FocusEvent e) {
  96:         if (e.getSource() instanceof JTextComponent) {
  97:             final JTextComponent tex = (JTextComponent) e.getSource();
  98:             tex.select(0, 0);
  99:         }
 100:     }
 101: 
 102:     /**
 103:      * Adds this instance as a listener for the specified text component.
 104:      * 
 105:      * @param t  the text component.
 106:      */
 107:     public static void addTextComponent(final JTextComponent t) {
 108:         if (singleton == null) {
 109:             singleton = new JTextObserver();
 110:         }
 111:         t.addFocusListener(singleton);
 112:     }
 113: 
 114:     /**
 115:      * Removes this instance as a listener for the specified text component.
 116:      * 
 117:      * @param t  the text component.
 118:      */
 119:    public static void removeTextComponent(final JTextComponent t) {
 120:         if (singleton == null) {
 121:             singleton = new JTextObserver();
 122:         }
 123:         t.removeFocusListener(singleton);
 124:     }
 125:     
 126: }