/*

 * Copyright (c) 2000, 2008, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

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);

    }

}