content: /* ========================================================================
   * JCommon : a free general purpose class library for the Java(tm) platform
   * ========================================================================
   *
   * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
   * 
   * Project Info:  http://www.jfree.org/jcommon/index.html
   *
   * This library is free software; you can redistribute it and/or modify it 
   * under the terms of the GNU Lesser General Public License as published by 
   * the Free Software Foundation; either version 2.1 of the License, or 
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but 
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
   * USA.  
   *
   * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
   * in the United States and other countries.]
   * 
   * ------------------
   * JTextObserver.java
   * ------------------
   * (C) Copyright 2004, by Thomas Morgner and Contributors.
   *
   * Original Author:  Thomas Morgner;
   * Contributor(s):   David Gilbert (for Object Refinery Limited);
   *
   * $Id: JTextObserver.java,v 1.6 2007/11/02 17:50:36 taqua Exp $
   *
   * Changes
   * -------
   * 07-Jun-2004 : Added JCommon header (DG);
   *
   */
  
  package org.jfree.ui;
  
  import java.awt.event.FocusEvent;
  import java.awt.event.FocusListener;
  import javax.swing.text.JTextComponent;
  
  /**
   * An observer that selects all the text when a field gains the focus.
   *
   * @author Thomas Morgner
   */
  public final class JTextObserver implements FocusListener {
  
      /** The singleton instance. */
      private static JTextObserver singleton;
  
      /**
       * Creates a new instance.
       */
      private JTextObserver() {
          // nothing required
      }
  
      /**
       * Returns the single instance.
       * 
       * @return The single instance.
       */
      public static JTextObserver getInstance() {
          if (singleton == null) {
             singleton = new JTextObserver();
          }
          return singleton;
      }
  
      /**
       * Selects all the text when a field gains the focus.
       * 
       * @param e  the focus event.
       */
      public void focusGained(final FocusEvent e) {
          if (e.getSource() instanceof JTextComponent) {
              final JTextComponent tex = (JTextComponent) e.getSource();
              tex.selectAll();
          }
      }
  
      /**
       * Deselects the text when a field loses the focus.
       * 
       * @param e  the event.
       */
      public void focusLost(final FocusEvent e) {
          if (e.getSource() instanceof JTextComponent) {
              final JTextComponent tex = (JTextComponent) e.getSource();
              tex.select(0, 0);
          }
      }
  
      /**
       * Adds this instance as a listener for the specified text component.
       * 
       * @param t  the text component.
       */
      public static void addTextComponent(final JTextComponent t) {
          if (singleton == null) {
              singleton = new JTextObserver();
          }
          t.addFocusListener(singleton);
      }
  
      /**
       * Removes this instance as a listener for the specified text component.
       * 
       * @param t  the text component.
       */
     public static void removeTextComponent(final JTextComponent t) {
          if (singleton == null) {
              singleton = new JTextObserver();
          }
          t.removeFocusListener(singleton);
      }
      
  }
  