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    1   /*
    2    * Copyright (c) 1997, 2008, Oracle and/or its affiliates. All rights reserved.
    3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
    4    *
    5    * This code is free software; you can redistribute it and/or modify it
    6    * under the terms of the GNU General Public License version 2 only, as
    7    * published by the Free Software Foundation.  Oracle designates this
    8    * particular file as subject to the "Classpath" exception as provided
    9    * by Oracle in the LICENSE file that accompanied this code.
   10    *
   11    * This code is distributed in the hope that it will be useful, but WITHOUT
   12    * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   13    * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   14    * version 2 for more details (a copy is included in the LICENSE file that
   15    * accompanied this code).
   16    *
   17    * You should have received a copy of the GNU General Public License version
   18    * 2 along with this work; if not, write to the Free Software Foundation,
   19    * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   20    *
   21    * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   22    * or visit www.oracle.com if you need additional information or have any
   23    * questions.
   24    */
   25   
   26   package javax.swing;
   27   
   28   import javax.swing.event;
   29   import java.io.Serializable;
   30   import java.util.EventListener;
   31   
   32   /**
   33    * A generic implementation of SingleSelectionModel.
   34    * <p>
   35    * <strong>Warning:</strong>
   36    * Serialized objects of this class will not be compatible with
   37    * future Swing releases. The current serialization support is
   38    * appropriate for short term storage or RMI between applications running
   39    * the same version of Swing.  As of 1.4, support for long term storage
   40    * of all JavaBeans<sup><font size="-2">TM</font></sup>
   41    * has been added to the <code>java.beans</code> package.
   42    * Please see {@link java.beans.XMLEncoder}.
   43    *
   44    * @author Dave Moore
   45    */
   46   public class DefaultSingleSelectionModel implements SingleSelectionModel,
   47   Serializable {
   48       /* Only one ModelChangeEvent is needed per model instance since the
   49        * event's only (read-only) state is the source property.  The source
   50        * of events generated here is always "this".
   51        */
   52       protected transient ChangeEvent changeEvent = null;
   53       /** The collection of registered listeners */
   54       protected EventListenerList listenerList = new EventListenerList();
   55   
   56       private int index = -1;
   57   
   58       // implements javax.swing.SingleSelectionModel
   59       public int getSelectedIndex() {
   60           return index;
   61       }
   62   
   63       // implements javax.swing.SingleSelectionModel
   64       public void setSelectedIndex(int index) {
   65           if (this.index != index) {
   66               this.index = index;
   67               fireStateChanged();
   68           }
   69       }
   70   
   71       // implements javax.swing.SingleSelectionModel
   72       public void clearSelection() {
   73           setSelectedIndex(-1);
   74       }
   75   
   76       // implements javax.swing.SingleSelectionModel
   77       public boolean isSelected() {
   78           boolean ret = false;
   79           if (getSelectedIndex() != -1) {
   80               ret = true;
   81           }
   82           return ret;
   83       }
   84   
   85       /**
   86        * Adds a <code>ChangeListener</code> to the button.
   87        */
   88       public void addChangeListener(ChangeListener l) {
   89           listenerList.add(ChangeListener.class, l);
   90       }
   91   
   92       /**
   93        * Removes a <code>ChangeListener</code> from the button.
   94        */
   95       public void removeChangeListener(ChangeListener l) {
   96           listenerList.remove(ChangeListener.class, l);
   97       }
   98   
   99       /**
  100        * Returns an array of all the change listeners
  101        * registered on this <code>DefaultSingleSelectionModel</code>.
  102        *
  103        * @return all of this model's <code>ChangeListener</code>s
  104        *         or an empty
  105        *         array if no change listeners are currently registered
  106        *
  107        * @see #addChangeListener
  108        * @see #removeChangeListener
  109        *
  110        * @since 1.4
  111        */
  112       public ChangeListener[] getChangeListeners() {
  113           return listenerList.getListeners(ChangeListener.class);
  114       }
  115   
  116       /**
  117        * Notifies all listeners that have registered interest for
  118        * notification on this event type.  The event instance
  119        * is created lazily.
  120        * @see EventListenerList
  121        */
  122       protected void fireStateChanged() {
  123           // Guaranteed to return a non-null array
  124           Object[] listeners = listenerList.getListenerList();
  125           // Process the listeners last to first, notifying
  126           // those that are interested in this event
  127           for (int i = listeners.length-2; i>=0; i-=2) {
  128               if (listeners[i]==ChangeListener.class) {
  129                   // Lazily create the event:
  130                   if (changeEvent == null)
  131                       changeEvent = new ChangeEvent(this);
  132                   ((ChangeListener)listeners[i+1]).stateChanged(changeEvent);
  133               }
  134           }
  135       }
  136   
  137       /**
  138        * Returns an array of all the objects currently registered as
  139        * <code><em>Foo</em>Listener</code>s
  140        * upon this model.
  141        * <code><em>Foo</em>Listener</code>s
  142        * are registered using the <code>add<em>Foo</em>Listener</code> method.
  143        * <p>
  144        * You can specify the <code>listenerType</code> argument
  145        * with a class literal, such as <code><em>Foo</em>Listener.class</code>.
  146        * For example, you can query a <code>DefaultSingleSelectionModel</code>
  147        * instance <code>m</code>
  148        * for its change listeners
  149        * with the following code:
  150        *
  151        * <pre>ChangeListener[] cls = (ChangeListener[])(m.getListeners(ChangeListener.class));</pre>
  152        *
  153        * If no such listeners exist,
  154        * this method returns an empty array.
  155        *
  156        * @param listenerType  the type of listeners requested;
  157        *          this parameter should specify an interface
  158        *          that descends from <code>java.util.EventListener</code>
  159        * @return an array of all objects registered as
  160        *          <code><em>Foo</em>Listener</code>s
  161        *          on this model,
  162        *          or an empty array if no such
  163        *          listeners have been added
  164        * @exception ClassCastException if <code>listenerType</code> doesn't
  165        *          specify a class or interface that implements
  166        *          <code>java.util.EventListener</code>
  167        *
  168        * @see #getChangeListeners
  169        *
  170        * @since 1.3
  171        */
  172       public <T extends EventListener> T[] getListeners(Class<T> listenerType) {
  173           return listenerList.getListeners(listenerType);
  174       }
  175   }

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