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 * DefaultKeyedValue.java
029 * ----------------------
030 * (C) Copyright 2002-2008, by Object Refinery Limited.
031 *
032 * Original Author:  David Gilbert (for Object Refinery Limited);
033 * Contributor(s):   -;
034 *
035 * Changes:
036 * --------
037 * 31-Oct-2002 : Version 1 (DG);
038 * 13-Mar-2003 : Added equals() method, and implemented Serializable (DG);
039 * 18-Aug-2003 : Implemented Cloneable (DG);
040 * 18-Aug-2004 : Moved from org.jfree.data --> org.jfree.data.base (DG);
041 * 15-Sep-2004 : Added PublicCloneable interface (DG);
042 * ------------- JFREECHART 1.0.x ---------------------------------------------
043 * 11-Jun-2007 : Added toString() method to help with debugging (DG);
044 * 15-Feb-2008 : Prevent null key (DG);
045 * 07-Apr-2008 : Removed to-do item (DG);
046 *
047 */
048
049package org.jfree.data;
050
051import java.io.Serializable;
052
053import org.jfree.util.PublicCloneable;
054
055/**
056 * A (key, value) pair.  This class provides a default implementation
057 * of the {@link KeyedValue} interface.
058 */
059public class DefaultKeyedValue implements KeyedValue, Cloneable,
060        PublicCloneable, Serializable {
061
062    /** For serialization. */
063    private static final long serialVersionUID = -7388924517460437712L;
064
065    /** The key. */
066    private Comparable key;
067
068    /** The value. */
069    private Number value;
070
071    /**
072     * Creates a new (key, value) item.
073     *
074     * @param key  the key (should be immutable, <code>null</code> not
075     *         permitted).
076     * @param value  the value (<code>null</code> permitted).
077     */
078    public DefaultKeyedValue(Comparable key, Number value) {
079        if (key == null) {
080            throw new IllegalArgumentException("Null 'key' argument.");
081        }
082        this.key = key;
083        this.value = value;
084    }
085
086    /**
087     * Returns the key.
088     *
089     * @return The key (never <code>null</code>).
090     */
091    public Comparable getKey() {
092        return this.key;
093    }
094
095    /**
096     * Returns the value.
097     *
098     * @return The value (possibly <code>null</code>).
099     */
100    public Number getValue() {
101        return this.value;
102    }
103
104    /**
105     * Sets the value.
106     *
107     * @param value  the value (<code>null</code> permitted).
108     */
109    public synchronized void setValue(Number value) {
110        this.value = value;
111    }
112
113    /**
114     * Tests this key-value pair for equality with an arbitrary object.
115     *
116     * @param obj  the object (<code>null</code> permitted).
117     *
118     * @return A boolean.
119     */
120    public boolean equals(Object obj) {
121        if (obj == this) {
122            return true;
123        }
124        if (!(obj instanceof DefaultKeyedValue)) {
125            return false;
126        }
127        DefaultKeyedValue that = (DefaultKeyedValue) obj;
128
129        if (!this.key.equals(that.key)) {
130            return false;
131        }
132        if (this.value != null
133                ? !this.value.equals(that.value) : that.value != null) {
134            return false;
135        }
136        return true;
137    }
138
139    /**
140     * Returns a hash code.
141     *
142     * @return A hash code.
143     */
144    public int hashCode() {
145        int result;
146        result = (this.key != null ? this.key.hashCode() : 0);
147        result = 29 * result + (this.value != null ? this.value.hashCode() : 0);
148        return result;
149    }
150
151    /**
152     * Returns a clone.  It is assumed that both the key and value are
153     * immutable objects, so only the references are cloned, not the objects
154     * themselves.
155     *
156     * @return A clone.
157     *
158     * @throws CloneNotSupportedException Not thrown by this class, but
159     *         subclasses (if any) might.
160     */
161    public Object clone() throws CloneNotSupportedException {
162        DefaultKeyedValue clone = (DefaultKeyedValue) super.clone();
163        return clone;
164    }
165
166    /**
167     * Returns a string representing this instance, primarily useful for
168     * debugging.
169     *
170     * @return A string.
171     */
172    public String toString() {
173        return "(" + this.key.toString() + ", " + this.value.toString() + ")";
174    }
175
176}