001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2008, 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 2003-2008, 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}