Source for javax.swing.DefaultSingleSelectionModel

   1: /* DefaultSingleSelectionModel.java --
   2:    Copyright (C) 2002, 2004, 2006,  Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package javax.swing;
  40: 
  41: import java.io.Serializable;
  42: import java.util.EventListener;
  43: 
  44: import javax.swing.event.ChangeEvent;
  45: import javax.swing.event.ChangeListener;
  46: import javax.swing.event.EventListenerList;
  47: 
  48: /**
  49:  * The default implementation of {@link SingleSelectionModel}, used in
  50:  * {@link JTabbedPane}, {@link JMenuBar} and {@link JPopupMenu}.
  51:  *
  52:  * @author Andrew Selkirk
  53:  */
  54: public class DefaultSingleSelectionModel
  55:   implements SingleSelectionModel, Serializable
  56: {
  57:   private static final long serialVersionUID = 3676229404753786004L;
  58: 
  59:   /**
  60:    * changeEvent
  61:    */
  62:   protected transient ChangeEvent changeEvent;
  63: 
  64:   /**
  65:    * listenerList
  66:    */
  67:   protected EventListenerList listenerList = new EventListenerList();
  68: 
  69:   /**
  70:    * The selected index (or -1 for no selection).
  71:    */
  72:   private int index = -1;
  73: 
  74:   /**
  75:    * Creates a new <code>DefaultSingleSelectionModel</code> with no current
  76:    * selection.
  77:    */
  78:   public DefaultSingleSelectionModel()
  79:   {
  80:     // Do nothing.
  81:   }
  82: 
  83:   /**
  84:    * Returns the selected index or <code>-1</code> if there is no selection.
  85:    *
  86:    * @return The selected index.
  87:    *
  88:    * @see #setSelectedIndex(int)
  89:    */
  90:   public int getSelectedIndex()
  91:   {
  92:     return index;
  93:   }
  94: 
  95:   /**
  96:    * Sets the selected index and, if this is different to the previous
  97:    * selection, sends a {@link ChangeEvent} to all registered listeners.
  98:    *
  99:    * @param index  the index (use <code>-1</code> to represent no selection).
 100:    *
 101:    * @see #getSelectedIndex()
 102:    * @see #clearSelection
 103:    */
 104:   public void setSelectedIndex(int index)
 105:   {
 106:     if (this.index != index)
 107:       {
 108:         this.index = index;
 109:         fireStateChanged();
 110:       }
 111:   }
 112: 
 113:   /**
 114:    * Clears the selection by setting the selected index to <code>-1</code> and
 115:    * sends a {@link ChangeEvent} to all registered listeners.  If the selected
 116:    * index is already <code>-1</code>, this method does nothing.
 117:    */
 118:   public void clearSelection()
 119:   {
 120:     setSelectedIndex(-1);
 121:   }
 122: 
 123:   /**
 124:    * Returns <code>true</code> if there is a selection, and <code>false</code>
 125:    * otherwise.
 126:    *
 127:    * @return A boolean.
 128:    */
 129:   public boolean isSelected()
 130:   {
 131:     return index != -1;
 132:   }
 133: 
 134:   /**
 135:    * Registers a listener to receive {@link ChangeEvent} notifications from
 136:    * this model whenever the selected index changes.
 137:    *
 138:    * @param listener the listener to add.
 139:    */
 140:   public void addChangeListener(ChangeListener listener)
 141:   {
 142:     listenerList.add(ChangeListener.class, listener);
 143:   }
 144: 
 145:   /**
 146:    * Deregisters a listener so that it no longer receives {@link ChangeEvent}
 147:    * notifications from this model.
 148:    *
 149:    * @param listener the listener to remove.
 150:    */
 151:   public void removeChangeListener(ChangeListener listener)
 152:   {
 153:     listenerList.remove(ChangeListener.class, listener);
 154:   }
 155: 
 156:   /**
 157:    * fireStateChanged
 158:    */
 159:   protected void fireStateChanged()
 160:   {
 161:     if (changeEvent == null)
 162:       changeEvent = new ChangeEvent(this);
 163:     ChangeListener[] listeners = getChangeListeners();
 164:     for (int i = 0; i < listeners.length; i++)
 165:       listeners[i].stateChanged(changeEvent);
 166:   }
 167: 
 168:   /**
 169:    * getListeners
 170:    *
 171:    * @param listenerClass the type fo listener
 172:    *
 173:    * @return an array of listeners
 174:    *
 175:    * @since 1.3
 176:    */
 177:   public <T extends EventListener> T[] getListeners(Class<T> listenerClass)
 178:   {
 179:     return listenerList.getListeners(listenerClass);
 180:   }
 181: 
 182:   /**
 183:    * getChangeListeners
 184:    *
 185:    * @since 1.4
 186:    */
 187:   public ChangeListener[] getChangeListeners()
 188:   {
 189:     return (ChangeListener[]) getListeners(ChangeListener.class);
 190:   }
 191: }