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jfreechart example source code file (AbstractOverlay.java)

This example jfreechart source code file (AbstractOverlay.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - jfreechart tags/keywords

abstractoverlay, abstractoverlay, event, eventlistenerlist, gui, illegalargumentexception, illegalargumentexception, null, null, object, overlaychangeevent, overlaychangeevent, overlaychangelistener, swing

The jfreechart AbstractOverlay.java source code

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2009, by Object Refinery Limited and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * --------------------
 * AbstractOverlay.java
 * --------------------
 * (C) Copyright 2009, by Object Refinery Limited.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * Changes:
 * --------
 * 09-Apr-2009 : Version 1 (DG);
 *
 */

package org.jfree.chart.panel;

import javax.swing.event.EventListenerList;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.event.ChartChangeEvent;
import org.jfree.chart.event.OverlayChangeEvent;
import org.jfree.chart.event.OverlayChangeListener;

/**
 * A base class for implementing overlays for a {@link ChartPanel}.
 *
 * @since 1.0.13
 */
public class AbstractOverlay {

    /** Storage for registered change listeners. */
    private transient EventListenerList changeListeners;

    /**
     * Default constructor.
     */
    public AbstractOverlay() {
        this.changeListeners = new EventListenerList();
    }

    /**
     * Registers an object for notification of changes to the overlay.
     *
     * @param listener  the listener (<code>null not permitted).
     *
     * @see #removeChangeListener(OverlayChangeListener)
     */
    public void addChangeListener(OverlayChangeListener listener) {
        if (listener == null) {
            throw new IllegalArgumentException("Null 'listener' argument.");
        }
        this.changeListeners.add(OverlayChangeListener.class, listener);
    }

    /**
     * Deregisters an object for notification of changes to the overlay.
     *
     * @param listener  the listener (<code>null not permitted)
     *
     * @see #addChangeListener(OverlayChangeListener)
     */
    public void removeChangeListener(OverlayChangeListener listener) {
        if (listener == null) {
            throw new IllegalArgumentException("Null 'listener' argument.");
        }
        this.changeListeners.remove(OverlayChangeListener.class, listener);
    }

    /**
     * Sends a default {@link ChartChangeEvent} to all registered listeners.
     * <P>
     * This method is for convenience only.
     */
    public void fireOverlayChanged() {
        OverlayChangeEvent event = new OverlayChangeEvent(this);
        notifyListeners(event);
    }

    /**
     * Sends a {@link ChartChangeEvent} to all registered listeners.
     *
     * @param event  information about the event that triggered the
     *               notification.
     */
    protected void notifyListeners(OverlayChangeEvent event) {
       Object[] listeners = this.changeListeners.getListenerList();
        for (int i = listeners.length - 2; i >= 0; i -= 2) {
            if (listeners[i] == OverlayChangeListener.class) {
                ((OverlayChangeListener) listeners[i + 1]).overlayChanged(
                        event);
            }
        }
    }

}

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