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
049 package org.jfree.data;
050
051 import java.io.Serializable;
052
053 import org.jfree.util.PublicCloneable;
054
055 /**
056 * A (key, value) pair. This class provides a default implementation
057 * of the {@link KeyedValue} interface.
058 */
059 public 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 }