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 * DefaultValueDataset.java
029 * ------------------------
030 * (C) Copyright 2003-2008, by Object Refinery Limited.
031 *
032 * Original Author: David Gilbert (for Object Refinery Limited);
033 * Contributor(s): -;
034 *
035 * Changes
036 * -------
037 * 27-Mar-2003 : Version 1 (DG);
038 * 18-Aug-2003 : Implemented Cloneable (DG);
039 * 03-Mar-2005 : Implemented PublicCloneable (DG);
040 * ------------- JFREECHART 1.0.x ---------------------------------------------
041 * 30-Jan-2007 : Added explicit super() call in constructor (for clarity) (DG);
042 *
043 */
044
045 package org.jfree.data.general;
046
047 import java.io.Serializable;
048
049 import org.jfree.util.ObjectUtilities;
050 import org.jfree.util.PublicCloneable;
051
052 /**
053 * A dataset that stores a single value (that is possibly <code>null</code>).
054 * This class provides a default implementation of the {@link ValueDataset}
055 * interface.
056 */
057 public class DefaultValueDataset extends AbstractDataset
058 implements ValueDataset, Cloneable, PublicCloneable, Serializable {
059
060 /** For serialization. */
061 private static final long serialVersionUID = 8137521217249294891L;
062
063 /** The value. */
064 private Number value;
065
066 /**
067 * Constructs a new dataset, initially empty.
068 */
069 public DefaultValueDataset() {
070 this(null);
071 }
072
073 /**
074 * Creates a new dataset with the specified value.
075 *
076 * @param value the value.
077 */
078 public DefaultValueDataset(double value) {
079 this(new Double(value));
080 }
081
082 /**
083 * Creates a new dataset with the specified value.
084 *
085 * @param value the initial value (<code>null</code> permitted).
086 */
087 public DefaultValueDataset(Number value) {
088 super();
089 this.value = value;
090 }
091
092 /**
093 * Returns the value.
094 *
095 * @return The value (possibly <code>null</code>).
096 */
097 public Number getValue() {
098 return this.value;
099 }
100
101 /**
102 * Sets the value and sends a {@link DatasetChangeEvent} to all registered
103 * listeners.
104 *
105 * @param value the new value (<code>null</code> permitted).
106 */
107 public void setValue(Number value) {
108 this.value = value;
109 notifyListeners(new DatasetChangeEvent(this, this));
110 }
111
112 /**
113 * Tests this dataset for equality with an arbitrary object.
114 *
115 * @param obj the object (<code>null</code> permitted).
116 *
117 * @return A boolean.
118 */
119 public boolean equals(Object obj) {
120 if (obj == this) {
121 return true;
122 }
123 if (obj instanceof ValueDataset) {
124 ValueDataset vd = (ValueDataset) obj;
125 return ObjectUtilities.equal(this.value, vd.getValue());
126 }
127 return false;
128 }
129
130 /**
131 * Returns a hash code.
132 *
133 * @return A hash code.
134 */
135 public int hashCode() {
136 return (this.value != null ? this.value.hashCode() : 0);
137 }
138
139 }