001    /* ===========================================================
002     * JFreeChart : a free chart library for the Java(tm) platform
003     * ===========================================================
004     *
005     * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
006     *
007     * Project Info:  http://www.jfree.org/jfreechart/index.html
008     *
009     * This library is free software; you can redistribute it and/or modify it 
010     * under the terms of the GNU Lesser General Public License as published by 
011     * the Free Software Foundation; either version 2.1 of the License, or 
012     * (at your option) any later version.
013     *
014     * This library is distributed in the hope that it will be useful, but 
015     * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
016     * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
017     * License for more details.
018     *
019     * You should have received a copy of the GNU Lesser General Public
020     * License along with this library; if not, write to the Free Software
021     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
022     * USA.  
023     *
024     * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
025     * in the United States and other countries.]
026     *
027     * -----------------------
028     * DatasetChangeEvent.java
029     * -----------------------
030     * (C) Copyright 2000-2004, by Object Refinery Limited.
031     *
032     * Original Author:  David Gilbert (for Object Refinery Limited);
033     * Contributor(s):   -;
034     *
035     * $Id: DatasetChangeEvent.java,v 1.3.2.1 2005/10/25 21:32:29 mungady Exp $
036     *
037     * Changes (from 24-Aug-2001)
038     * --------------------------
039     * 24-Aug-2001 : Added standard source header. Fixed DOS encoding problem (DG);
040     * 15-Oct-2001 : Move to new package (com.jrefinery.data.*) (DG);
041     * 22-Oct-2001 : Renamed DataSource.java --> Dataset.java etc. (DG);
042     * 11-Jun-2002 : Separated the event source from the dataset to cover the case 
043     *               where the dataset is changed to null in the Plot class.  
044     *               Updated Javadocs (DG);
045     * 04-Oct-2002 : Fixed errors reported by Checkstyle (DG);
046     * 05-Oct-2004 : Minor Javadoc updates (DG);
047     *
048     */
049    
050    package org.jfree.data.general;
051    
052    /**
053     * A change event that encapsulates information about a change to a dataset.
054     */
055    public class DatasetChangeEvent extends java.util.EventObject {
056    
057        /**
058         * The dataset that generated the change event.
059         */
060        private Dataset dataset;
061    
062        /**
063         * Constructs a new event.  The source is either the dataset or the 
064         * {@link org.jfree.chart.plot.Plot} class.  The dataset can be 
065         * <code>null</code> (in this case the source will be the 
066         * {@link org.jfree.chart.plot.Plot} class).
067         *
068         * @param source  the source of the event.
069         * @param dataset  the dataset that generated the event (<code>null</code>
070         *                 permitted).
071         */
072        public DatasetChangeEvent(Object source, Dataset dataset) {
073            super(source);
074            this.dataset = dataset;
075        }
076    
077        /**
078         * Returns the dataset that generated the event.  Note that the dataset
079         * may be <code>null</code> since adding a <code>null</code> dataset to a 
080         * plot will generated a change event.
081         *
082         * @return The dataset (possibly <code>null</code>).
083         */
084        public Dataset getDataset() {
085            return this.dataset;
086        }
087    
088    }