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 * DefaultValueDataset.java
029 * ------------------------
030 * (C) Copyright 2003-2007, by Object Refinery Limited.
031 *
032 * Original Author: David Gilbert (for Object Refinery Limited);
033 * Contributor(s): -;
034 *
035 * $Id $
036 *
037 * Changes
038 * -------
039 * 27-Mar-2003 : Version 1 (DG);
040 * 18-Aug-2003 : Implemented Cloneable (DG);
041 * 03-Mar-2005 : Implemented PublicCloneable (DG);
042 * ------------- JFREECHART 1.0.x ---------------------------------------------
043 * 30-Jan-2007 : Added explicit super() call in constructor (for clarity) (DG);
044 *
045 */
046
047 package org.jfree.data.general;
048
049 import java.io.Serializable;
050
051 import org.jfree.util.ObjectUtilities;
052 import org.jfree.util.PublicCloneable;
053
054 /**
055 * A dataset that stores a single value (that is possibly <code>null</code>).
056 * This class provides a default implementation of the {@link ValueDataset}
057 * interface.
058 */
059 public class DefaultValueDataset extends AbstractDataset
060 implements ValueDataset,
061 Cloneable, PublicCloneable,
062 Serializable {
063
064 /** For serialization. */
065 private static final long serialVersionUID = 8137521217249294891L;
066
067 /** The value. */
068 private Number value;
069
070 /**
071 * Constructs a new dataset, initially empty.
072 */
073 public DefaultValueDataset() {
074 this(null);
075 }
076
077 /**
078 * Creates a new dataset with the specified value.
079 *
080 * @param value the value.
081 */
082 public DefaultValueDataset(double value) {
083 this(new Double(value));
084 }
085
086 /**
087 * Creates a new dataset with the specified value.
088 *
089 * @param value the initial value (<code>null</code> permitted).
090 */
091 public DefaultValueDataset(Number value) {
092 super();
093 this.value = value;
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 and sends a {@link DatasetChangeEvent} to all registered
107 * listeners.
108 *
109 * @param value the new value (<code>null</code> permitted).
110 */
111 public void setValue(Number value) {
112 this.value = value;
113 notifyListeners(new DatasetChangeEvent(this, this));
114 }
115
116 /**
117 * Tests this dataset for equality with an arbitrary object.
118 *
119 * @param obj the object (<code>null</code> permitted).
120 *
121 * @return A boolean.
122 */
123 public boolean equals(Object obj) {
124 if (obj == this) {
125 return true;
126 }
127 if (obj instanceof ValueDataset) {
128 ValueDataset vd = (ValueDataset) obj;
129 return ObjectUtilities.equal(this.value, vd.getValue());
130 }
131 return false;
132 }
133
134 /**
135 * Returns a hash code.
136 *
137 * @return A hash code.
138 */
139 public int hashCode() {
140 return (this.value != null ? this.value.hashCode() : 0);
141 }
142
143 }