/*
 * Copyright (c) 2000, 2008, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package javax.swing;

import java.util.*;
import javax.swing.event.*;
import java.io.Serializable;


/**
 * This class provides the ChangeListener part of the
 * SpinnerModel interface that should be suitable for most concrete SpinnerModel
 * implementations. Subclasses must provide an implementation of the
 * <code>setValue</code>, <code>getValue</code>, <code>getNextValue</code> and
 * <code>getPreviousValue</code> methods.
 *
 * @see JSpinner
 * @see SpinnerModel
 * @see SpinnerListModel
 * @see SpinnerNumberModel
 * @see SpinnerDateModel
 *
 * @author Hans Muller
 * @since 1.4
 */
public abstract class AbstractSpinnerModel implements SpinnerModel, Serializable
{

 /**
 * Only one ChangeEvent is needed per model instance since the
 * event's only (read-only) state is the source property. The source
 * of events generated here is always "this".
 */
 private transient ChangeEvent changeEvent = null;


 /**
 * The list of ChangeListeners for this model. Subclasses may
 * store their own listeners here.
 */
 protected EventListenerList listenerList = new EventListenerList();


 /**
 * Adds a ChangeListener to the model's listener list. The
 * ChangeListeners must be notified when the models value changes.
 *
 * @param l the ChangeListener to add
 * @see #removeChangeListener
 * @see SpinnerModel#addChangeListener
 */
 public void addChangeListener(ChangeListener l) {
 listenerList.add(ChangeListener.class, l);
 }


 /**
 * Removes a ChangeListener from the model's listener list.
 *
 * @param l the ChangeListener to remove
 * @see #addChangeListener
 * @see SpinnerModel#removeChangeListener
 */
 public void removeChangeListener(ChangeListener l) {
 listenerList.remove(ChangeListener.class, l);
 }


 /**
 * Returns an array of all the <code>ChangeListener</code>s added
 * to this AbstractSpinnerModel with addChangeListener().
 *
 * @return all of the <code>ChangeListener</code>s added or an empty
 * array if no listeners have been added
 * @since 1.4
 */
 public ChangeListener[] getChangeListeners() {
 return listenerList.getListeners(ChangeListener.class);
 }


 /**
 * Run each ChangeListeners stateChanged() method.
 *
 * @see #setValue
 * @see EventListenerList
 */
 protected void fireStateChanged()
 {
 Object[] listeners = listenerList.getListenerList();
 for (int i = listeners.length - 2; i >= 0; i -=2 ) {
 if (listeners[i] == ChangeListener.class) {
 if (changeEvent == null) {
 changeEvent = new ChangeEvent(this);
 }
 ((ChangeListener)listeners[i+1]).stateChanged(changeEvent);
 }
 }
 }


 /**
 * Return an array of all the listeners of the given type that
 * were added to this model. For example to find all of the
 * ChangeListeners added to this model:
 * <pre>
 * myAbstractSpinnerModel.getListeners(ChangeListener.class);
 * </pre>
 *
 * @param listenerType the type of listeners to return, e.g. ChangeListener.class
 * @return all of the objects receiving <em>listenerType</em> notifications
 * from this model
 */
 public <T extends EventListener> T[] getListeners(Class<T> listenerType) {
 return listenerList.getListeners(listenerType);
 }
}