001/* DefaultSingleSelectionModel.java --
002   Copyright (C) 2002, 2004, 2006,  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package javax.swing;
040
041import java.io.Serializable;
042import java.util.EventListener;
043
044import javax.swing.event.ChangeEvent;
045import javax.swing.event.ChangeListener;
046import javax.swing.event.EventListenerList;
047
048/**
049 * The default implementation of {@link SingleSelectionModel}, used in
050 * {@link JTabbedPane}, {@link JMenuBar} and {@link JPopupMenu}.
051 *
052 * @author Andrew Selkirk
053 */
054public class DefaultSingleSelectionModel
055  implements SingleSelectionModel, Serializable
056{
057  private static final long serialVersionUID = 3676229404753786004L;
058
059  /**
060   * changeEvent
061   */
062  protected transient ChangeEvent changeEvent;
063
064  /**
065   * listenerList
066   */
067  protected EventListenerList listenerList = new EventListenerList();
068
069  /**
070   * The selected index (or -1 for no selection).
071   */
072  private int index = -1;
073
074  /**
075   * Creates a new <code>DefaultSingleSelectionModel</code> with no current
076   * selection.
077   */
078  public DefaultSingleSelectionModel()
079  {
080    // Do nothing.
081  }
082
083  /**
084   * Returns the selected index or <code>-1</code> if there is no selection.
085   *
086   * @return The selected index.
087   *
088   * @see #setSelectedIndex(int)
089   */
090  public int getSelectedIndex()
091  {
092    return index;
093  }
094
095  /**
096   * Sets the selected index and, if this is different to the previous
097   * selection, sends a {@link ChangeEvent} to all registered listeners.
098   *
099   * @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}