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 }