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,
060 Cloneable, PublicCloneable,
061 Serializable {
062
063 /** For serialization. */
064 private static final long serialVersionUID = -7388924517460437712L;
065
066 /** The key. */
067 private Comparable key;
068
069 /** The value. */
070 private Number value;
071
072 /**
073 * Creates a new (key, value) item.
074 *
075 * @param key the key (should be immutable, <code>null</code> not
076 * permitted).
077 * @param value the value (<code>null</code> permitted).
078 */
079 public DefaultKeyedValue(Comparable key, Number value) {
080 if (key == null) {
081 throw new IllegalArgumentException("Null 'key' argument.");
082 }
083 this.key = key;
084 this.value = value;
085 }
086
087 /**
088 * Returns the key.
089 *
090 * @return The key (never <code>null</code>).
091 */
092 public Comparable getKey() {
093 return this.key;
094 }
095
096 /**
097 * Returns the value.
098 *
099 * @return The value (possibly <code>null</code>).
100 */
101 public Number getValue() {
102 return this.value;
103 }
104
105 /**
106 * Sets the value.
107 *
108 * @param value the value (<code>null</code> permitted).
109 */
110 public synchronized void setValue(Number value) {
111 this.value = value;
112 }
113
114 /**
115 * Tests this key-value pair for equality with an arbitrary object.
116 *
117 * @param obj the object (<code>null</code> permitted).
118 *
119 * @return A boolean.
120 */
121 public boolean equals(Object obj) {
122 if (obj == this) {
123 return true;
124 }
125 if (!(obj instanceof DefaultKeyedValue)) {
126 return false;
127 }
128 DefaultKeyedValue that = (DefaultKeyedValue) obj;
129
130 if (!this.key.equals(that.key)) {
131 return false;
132 }
133 if (this.value != null
134 ? !this.value.equals(that.value) : that.value != null) {
135 return false;
136 }
137 return true;
138 }
139
140 /**
141 * Returns a hash code.
142 *
143 * @return A hash code.
144 */
145 public int hashCode() {
146 int result;
147 result = (this.key != null ? this.key.hashCode() : 0);
148 result = 29 * result + (this.value != null ? this.value.hashCode() : 0);
149 return result;
150 }
151
152 /**
153 * Returns a clone. It is assumed that both the key and value are
154 * immutable objects, so only the references are cloned, not the objects
155 * themselves.
156 *
157 * @return A clone.
158 *
159 * @throws CloneNotSupportedException Not thrown by this class, but
160 * subclasses (if any) might.
161 */
162 public Object clone() throws CloneNotSupportedException {
163 DefaultKeyedValue clone = (DefaultKeyedValue) super.clone();
164 return clone;
165 }
166
167 /**
168 * Returns a string representing this instance, primarily useful for
169 * debugging.
170 *
171 * @return A string.
172 */
173 public String toString() {
174 return "(" + this.key.toString() + ", " + this.value.toString() + ")";
175 }
176
177 }