001 /* DefaultSingleSelectionModel.java --
002 Copyright (C) 2002, 2004, 2006, Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package javax.swing;
040
041 import java.io.Serializable;
042 import java.util.EventListener;
043
044 import javax.swing.event.ChangeEvent;
045 import javax.swing.event.ChangeListener;
046 import 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 */
054 public 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 }