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 1.5 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;
  46: import java.awt.event.FocusListener;
  47: 
  48: import javax.swing.text.JTextComponent;
  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 {
  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 e) {
  85:         if (e.getSource() instanceof JTextComponent) {
  86:             final JTextComponent tex = (JTextComponent) 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 e) {
  97:         if (e.getSource() instanceof JTextComponent) {
  98:             final JTextComponent tex = (JTextComponent) 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 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: }