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/* @(#)AbstractStateModel.java
 * Copyright © 2002-05-09 Werner Randelshofer, Switzerland.
 * You may only use this software in accordance with the license terms.
 */
package ru.sbtqa.monte.media.beans;

import javax.swing.event.*;

/**
 * Abstract superclass of models that fire state change events to registered
 * ChangeListener's, when their state changes.
 *
 * @author Werner Randelshofer
 * @version 1.0 2002-05-09 Created.
 */
public class AbstractStateModel {

    protected EventListenerList listenerList;
    protected ChangeEvent changeEvent;

    /**
     * Creates a new instance of AbstractChangeModel
     */
    public AbstractStateModel() {
    }

    public void addChangeListener(ChangeListener l) {
        if (listenerList == null) {
            listenerList = new EventListenerList();
        }
        listenerList.add(ChangeListener.class, l);
    }

    public void removeChangeListener(ChangeListener l) {
        if (listenerList == null) {
            listenerList = new EventListenerList();
        }
        listenerList.remove(ChangeListener.class, l);
    }

    /**
     * Notify all listeners that have registered interest for notification on
     * this event type.
     */
    protected void fireStateChanged() {
        if (listenerList != null) {
            // Guaranteed to return a non-null array
            Object[] listeners = listenerList.getListenerList();
            // Process the listeners last to first, notifying
            // those that are interested in this event
            for (int i = listeners.length - 2; i >= 0; i -= 2) {
                if (listeners[i] == ChangeListener.class) {
                    // Lazily create the event:
                    if (changeEvent == null) {
                        changeEvent = new ChangeEvent(this);
                    }
                    ((ChangeListener) listeners[i + 1]).stateChanged(changeEvent);
                }
            }
        }
    }
}