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 * DefaultKeyedValueDataset.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 *
040 */
041
042package org.jfree.data.general;
043
044import java.io.Serializable;
045
046import org.jfree.data.DefaultKeyedValue;
047import org.jfree.data.KeyedValue;
048import org.jfree.util.ObjectUtilities;
049
050/**
051 * A default implementation of the {@link KeyedValueDataset} interface.
052 */
053public class DefaultKeyedValueDataset extends AbstractDataset
054        implements KeyedValueDataset, Serializable {
055
056    /** For serialization. */
057    private static final long serialVersionUID = -8149484339560406750L;
058
059    /** Storage for the data. */
060    private KeyedValue data;
061
062    /**
063     * Constructs a new dataset, initially empty.
064     */
065    public DefaultKeyedValueDataset() {
066        this(null);
067    }
068
069    /**
070     * Creates a new dataset with the specified initial value.
071     *
072     * @param key  the key.
073     * @param value  the value (<code>null</code> permitted).
074     */
075    public DefaultKeyedValueDataset(Comparable key, Number value) {
076        this(new DefaultKeyedValue(key, value));
077    }
078
079    /**
080     * Creates a new dataset that uses the data from a {@link KeyedValue}
081     * instance.
082     *
083     * @param data  the data (<code>null</code> permitted).
084     */
085    public DefaultKeyedValueDataset(KeyedValue data) {
086        this.data = data;
087    }
088
089    /**
090     * Returns the key associated with the value, or <code>null</code> if the
091     * dataset has no data item.
092     *
093     * @return The key.
094     */
095    public Comparable getKey() {
096        Comparable result = null;
097        if (this.data != null) {
098            result = this.data.getKey();
099        }
100        return result;
101    }
102
103    /**
104     * Returns the value.
105     *
106     * @return The value (possibly <code>null</code>).
107     */
108    public Number getValue() {
109        Number result = null;
110        if (this.data != null) {
111            result = this.data.getValue();
112        }
113        return result;
114    }
115
116    /**
117     * Updates the value.
118     *
119     * @param value  the new value (<code>null</code> permitted).
120     */
121    public void updateValue(Number value) {
122        if (this.data == null) {
123            throw new RuntimeException("updateValue: can't update null.");
124        }
125        setValue(this.data.getKey(), value);
126    }
127
128    /**
129     * Sets the value for the dataset and sends a {@link DatasetChangeEvent} to
130     * all registered listeners.
131     *
132     * @param key  the key.
133     * @param value  the value (<code>null</code> permitted).
134     */
135    public void setValue(Comparable key, Number value) {
136        this.data = new DefaultKeyedValue(key, value);
137        notifyListeners(new DatasetChangeEvent(this, this));
138    }
139
140    /**
141     * Tests this dataset for equality with an arbitrary object.
142     *
143     * @param obj  the object (<code>null</code> permitted).
144     *
145     * @return A boolean.
146     */
147    public boolean equals(Object obj) {
148        if (obj == this) {
149            return true;
150        }
151        if (!(obj instanceof KeyedValueDataset)) {
152            return false;
153        }
154        KeyedValueDataset that = (KeyedValueDataset) obj;
155        if (this.data == null) {
156            if (that.getKey() != null || that.getValue() != null) {
157                return false;
158            }
159            return true;
160        }
161        if (!ObjectUtilities.equal(this.data.getKey(), that.getKey())) {
162            return false;
163        }
164        if (!ObjectUtilities.equal(this.data.getValue(), that.getValue())) {
165            return false;
166        }
167        return true;
168    }
169
170    /**
171     * Returns a hash code.
172     *
173     * @return A hash code.
174     */
175    public int hashCode() {
176        return (this.data != null ? this.data.hashCode() : 0);
177    }
178
179    /**
180     * Creates a clone of the dataset.
181     *
182     * @return A clone.
183     *
184     * @throws CloneNotSupportedException This class will not throw this
185     *         exception, but subclasses (if any) might.
186     */
187    public Object clone() throws CloneNotSupportedException {
188        DefaultKeyedValueDataset clone
189                = (DefaultKeyedValueDataset) super.clone();
190        return clone;
191    }
192
193}