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    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   }

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