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    
047    package org.jfree.data;
048    
049    import java.io.Serializable;
050    
051    import org.jfree.util.PublicCloneable;
052    
053    /**
054     * A (key, value) pair.  This class provides a default implementation 
055     * of the {@link KeyedValue} interface.
056     */
057    public 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    }