    001    /* ===========================================================
    002     * JFreeChart : a free chart library for the Java(tm) platform
    003     * ===========================================================
    004     *
    005     * (C) Copyright 2000-2007, 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     * DefaultValueDataset.java
    029     * ------------------------
    030     * (C) Copyright 2003-2007, by Object Refinery Limited.
    031     *
    032     * Original Author:  David Gilbert (for Object Refinery Limited);
    033     * Contributor(s):   -;
    034     *
    035     * Changes
    036     * -------
    037     * 27-Mar-2003 : Version 1 (DG);
    038     * 18-Aug-2003 : Implemented Cloneable (DG);
    039     * 03-Mar-2005 : Implemented PublicCloneable (DG);
    040     * ------------- JFREECHART 1.0.x ---------------------------------------------
    041     * 30-Jan-2007 : Added explicit super() call in constructor (for clarity) (DG);
    042     *
    043     */
    044
    045    package org.jfree.data.general;
    046
    047    import java.io.Serializable;
    048
    049    import org.jfree.util.ObjectUtilities;
    050    import org.jfree.util.PublicCloneable;
    051
    052    /**
    053     * A dataset that stores a single value (that is possibly <code>null</code>).
    054     * This class provides a default implementation of the {@link ValueDataset}
    055     * interface.
    056     */
    057    public class DefaultValueDataset extends AbstractDataset
    058                                     implements ValueDataset,
    059                                                Cloneable, PublicCloneable,
    060                                                Serializable {
    061
    062        /** For serialization. */
    063        private static final long serialVersionUID = 8137521217249294891L;
    064
    065        /** The value. */
    066        private Number value;
    067
    068        /**
    069         * Constructs a new dataset, initially empty.
    070         */
    071        public DefaultValueDataset() {
    072            this(null);
    073        }
    074
    075        /**
    076         * Creates a new dataset with the specified value.
    077         *
    078         * @param value  the value.
    079         */
    080        public DefaultValueDataset(double value) {
    081            this(new Double(value));
    082        }
    083
    084        /**
    085         * Creates a new dataset with the specified value.
    086         *
    087         * @param value  the initial value (<code>null</code> permitted).
    088         */
    089        public DefaultValueDataset(Number value) {
    090            super();
    091            this.value = value;
    092        }
    093
    094        /**
    095         * Returns the value.
    096         *
    097         * @return The value (possibly <code>null</code>).
    098         */
    099        public Number getValue() {
    100            return this.value;
    101        }
    102
    103        /**
    104         * Sets the value and sends a {@link DatasetChangeEvent} to all registered
    105         * listeners.
    106         *
    107         * @param value  the new value (<code>null</code> permitted).
    108         */
    109        public void setValue(Number value) {
    110            this.value = value;
    111            notifyListeners(new DatasetChangeEvent(this, this));
    112        }
    113
    114        /**
    115         * Tests this dataset for equality with an arbitrary object.
    116         *
    117         * @param obj  the object (<code>null</code> permitted).
    118         *
    119         * @return A boolean.
    120         */
    121        public boolean equals(Object obj) {
    122            if (obj == this) {
    123                return true;
    124            }
    125            if (obj instanceof ValueDataset) {
    126                ValueDataset vd = (ValueDataset) obj;
    127                return ObjectUtilities.equal(this.value, vd.getValue());
    128            }
    129            return false;
    130        }
    131
    132        /**
    133         * Returns a hash code.
    134         *
    135         * @return A hash code.
    136         */
    137        public int hashCode() {
    138            return (this.value != null ? this.value.hashCode() : 0);
    139        }
    140
    141    }