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 * DefaultKeyedValue.java
029 * ----------------------
030 * (C) Copyright 2002-2007, 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 *
045 */
046
047package org.jfree.data;
048
049import java.io.Serializable;
050
051import org.jfree.util.PublicCloneable;
052
053/**
054 * A (key, value) pair.  This class provides a default implementation 
055 * of the {@link KeyedValue} interface.
056 */
057public class DefaultKeyedValue implements KeyedValue, 
058                                          Cloneable, PublicCloneable, 
059                                          Serializable {
060
061    /** For serialization. */
062    private static final long serialVersionUID = -7388924517460437712L;
063    
064    /** The key. */
065    private Comparable key;
066
067    /** The value. */
068    private Number value;
069
070    /**
071     * Creates a new (key, value) item.
072     *
073     * @param key  the key (should be immutable).
074     * @param value  the value (<code>null</code> permitted).
075     */
076    public DefaultKeyedValue(Comparable key, Number value) {
077        this.key = key;
078        this.value = value;
079    }
080
081    /**
082     * Returns the key.
083     *
084     * @return The key.
085     */
086    public Comparable getKey() {
087        return this.key;
088    }
089
090    /**
091     * Returns the value.
092     *
093     * @return The value (possibly <code>null</code>).
094     */
095    public Number getValue() {
096        return this.value;
097    }
098
099    /**
100     * Sets the value.
101     *
102     * @param value  the value (<code>null</code> permitted).
103     */
104    public synchronized void setValue(Number value) {
105        this.value = value;
106    }
107
108    /**
109     * Tests this key-value pair for equality with an arbitrary object.
110     *
111     * @param obj  the object (<code>null</code> permitted).
112     *
113     * @return A boolean.
114     */
115    public boolean equals(Object obj) {
116        if (obj == this) {
117            return true;
118        }
119        if (!(obj instanceof DefaultKeyedValue)) {
120            return false;
121        }
122        // TODO: modify this so that we check for equality with any KeyedValue
123        // rather than specifically a DefaultKeyedValue
124        DefaultKeyedValue that = (DefaultKeyedValue) obj;
125        
126        // TODO: the following checks for null should be handled in a utility 
127        // method
128        if (this.key != null ? !this.key.equals(that.key) : that.key != null) {
129            return false;
130        }
131        if (this.value != null 
132                ? !this.value.equals(that.value) : that.value != null) {
133            return false;
134        }
135        return true;
136    }
137
138    /**
139     * Returns a hash code.
140     * 
141     * @return A hash code.
142     */
143    public int hashCode() {
144        int result;
145        result = (this.key != null ? this.key.hashCode() : 0);
146        result = 29 * result + (this.value != null ? this.value.hashCode() : 0);
147        return result;
148    }
149
150    /**
151     * Returns a clone.  It is assumed that both the key and value are 
152     * immutable objects, so only the references are cloned, not the objects 
153     * themselves.
154     * 
155     * @return A clone.
156     * 
157     * @throws CloneNotSupportedException Not thrown by this class, but 
158     *         subclasses (if any) might.
159     */
160    public Object clone() throws CloneNotSupportedException {
161        DefaultKeyedValue clone = (DefaultKeyedValue) super.clone();
162        return clone;
163    }
164    
165    /** 
166     * Returns a string representing this instance, primarily useful for 
167     * debugging.
168     * 
169     * @return A string.
170     */
171    public String toString() {
172        return "(" + this.key.toString() + ", " + this.value.toString() + ")";
173    }
174
175}