    001/* ===========================================================
    002 * JFreeChart : a free chart library for the Java(tm) platform
    003 * ===========================================================
    004 *
    005 * (C) Copyright 2000-2011, 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 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
    025 * Other names may be trademarks of their respective owners.]
    026 *
    027 * ------------------------
    028 * DefaultValueDataset.java
    029 * ------------------------
    030 * (C) Copyright 2003-2008, 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
    045package org.jfree.data.general;
    046
    047import java.io.Serializable;
    048
    049import org.jfree.util.ObjectUtilities;
    050import 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 */
    057public class DefaultValueDataset extends AbstractDataset
    058        implements ValueDataset, Cloneable, PublicCloneable, Serializable {
    059
    060    /** For serialization. */
    061    private static final long serialVersionUID = 8137521217249294891L;
    062
    063    /** The value. */
    064    private Number value;
    065
    066    /**
    067     * Constructs a new dataset, initially empty.
    068     */
    069    public DefaultValueDataset() {
    070        this(null);
    071    }
    072
    073    /**
    074     * Creates a new dataset with the specified value.
    075     *
    076     * @param value  the value.
    077     */
    078    public DefaultValueDataset(double value) {
    079        this(new Double(value));
    080    }
    081
    082    /**
    083     * Creates a new dataset with the specified value.
    084     *
    085     * @param value  the initial value (<code>null</code> permitted).
    086     */
    087    public DefaultValueDataset(Number value) {
    088        super();
    089        this.value = value;
    090    }
    091
    092    /**
    093     * Returns the value.
    094     *
    095     * @return The value (possibly <code>null</code>).
    096     */
    097    public Number getValue() {
    098        return this.value;
    099    }
    100
    101    /**
    102     * Sets the value and sends a {@link DatasetChangeEvent} to all registered
    103     * listeners.
    104     *
    105     * @param value  the new value (<code>null</code> permitted).
    106     */
    107    public void setValue(Number value) {
    108        this.value = value;
    109        notifyListeners(new DatasetChangeEvent(this, this));
    110    }
    111
    112    /**
    113     * Tests this dataset for equality with an arbitrary object.
    114     *
    115     * @param obj  the object (<code>null</code> permitted).
    116     *
    117     * @return A boolean.
    118     */
    119    public boolean equals(Object obj) {
    120        if (obj == this) {
    121            return true;
    122        }
    123        if (obj instanceof ValueDataset) {
    124            ValueDataset vd = (ValueDataset) obj;
    125            return ObjectUtilities.equal(this.value, vd.getValue());
    126        }
    127        return false;
    128    }
    129
    130    /**
    131     * Returns a hash code.
    132     *
    133     * @return A hash code.
    134     */
    135    public int hashCode() {
    136        return (this.value != null ? this.value.hashCode() : 0);
    137    }
    138
    139}