1 /*
   2  * Copyright (c) 2000, 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 java.util.*;
  29 import javax.swing.event.*;
  30 import java.io.Serializable;
  31 
  32 
  33 /**
  34  * This class provides the ChangeListener part of the
  35  * SpinnerModel interface that should be suitable for most concrete SpinnerModel
  36  * implementations.  Subclasses must provide an implementation of the
  37  * <code>setValue</code>, <code>getValue</code>, <code>getNextValue</code> and
  38  * <code>getPreviousValue</code> methods.
  39  *
  40  * @see JSpinner
  41  * @see SpinnerModel
  42  * @see SpinnerListModel
  43  * @see SpinnerNumberModel
  44  * @see SpinnerDateModel
  45  *
  46  * @author Hans Muller
  47  * @since 1.4
  48  */
  49 public abstract class AbstractSpinnerModel implements SpinnerModel, Serializable
  50 {
  51 
  52     /**
  53      * Only one ChangeEvent is needed per model instance since the
  54      * event's only (read-only) state is the source property.  The source
  55      * of events generated here is always "this".
  56      */
  57     private transient ChangeEvent changeEvent = null;
  58 
  59 
  60     /**
  61      * The list of ChangeListeners for this model.  Subclasses may
  62      * store their own listeners here.
  63      */
  64     protected EventListenerList listenerList = new EventListenerList();
  65 
  66 
  67     /**
  68      * Adds a ChangeListener to the model's listener list.  The
  69      * ChangeListeners must be notified when the models value changes.
  70      *
  71      * @param l the ChangeListener to add
  72      * @see #removeChangeListener
  73      * @see SpinnerModel#addChangeListener
  74      */
  75     public void addChangeListener(ChangeListener l) {
  76         listenerList.add(ChangeListener.class, l);
  77     }
  78 
  79 
  80     /**
  81      * Removes a ChangeListener from the model's listener list.
  82      *
  83      * @param l the ChangeListener to remove
  84      * @see #addChangeListener
  85      * @see SpinnerModel#removeChangeListener
  86      */
  87     public void removeChangeListener(ChangeListener l) {
  88         listenerList.remove(ChangeListener.class, l);
  89     }
  90 
  91 
  92     /**
  93      * Returns an array of all the <code>ChangeListener</code>s added
  94      * to this AbstractSpinnerModel with addChangeListener().
  95      *
  96      * @return all of the <code>ChangeListener</code>s added or an empty
  97      *         array if no listeners have been added
  98      * @since 1.4
  99      */
 100     public ChangeListener[] getChangeListeners() {
 101         return listenerList.getListeners(ChangeListener.class);
 102     }
 103 
 104 
 105     /**
 106      * Run each ChangeListeners stateChanged() method.
 107      *
 108      * @see #setValue
 109      * @see EventListenerList
 110      */
 111     protected void fireStateChanged()
 112     {
 113         Object[] listeners = listenerList.getListenerList();
 114         for (int i = listeners.length - 2; i >= 0; i -=2 ) {
 115             if (listeners[i] == ChangeListener.class) {
 116                 if (changeEvent == null) {
 117                     changeEvent = new ChangeEvent(this);
 118                 }
 119                 ((ChangeListener)listeners[i+1]).stateChanged(changeEvent);
 120             }
 121         }
 122     }
 123 
 124 
 125     /**
 126      * Return an array of all the listeners of the given type that
 127      * were added to this model.  For example to find all of the
 128      * ChangeListeners added to this model:
 129      * <pre>
 130      * myAbstractSpinnerModel.getListeners(ChangeListener.class);
 131      * </pre>
 132      *
 133      * @param listenerType the type of listeners to return, e.g. ChangeListener.class
 134      * @return all of the objects receiving <em>listenerType</em> notifications
 135      *         from this model
 136      */
 137     public <T extends EventListener> T[] getListeners(Class<T> listenerType) {
 138         return listenerList.getListeners(listenerType);
 139     }
 140 }