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Java > Open Source Codes > org > jfree > data > general > DefaultValueDataset


1 /* ===========================================================
2  * JFreeChart : a free chart library for the Java(tm) platform
3  * ===========================================================
4  *
5  * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
6  *
7  * Project Info: http://www.jfree.org/jfreechart/index.html
8  *
9  * This library is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU Lesser General Public License as published by
11  * the Free Software Foundation; either version 2.1 of the License, or
12  * (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17  * License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
22  * USA.
23  *
24  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
25  * in the United States and other countries.]
26  *
27  * ------------------------
28  * DefaultValueDataset.java
29  * ------------------------
30  * (C) Copyright 2003-2005, by Object Refinery Limited.
31  *
32  * Original Author: David Gilbert (for Object Refinery Limited);
33  * Contributor(s): -;
34  *
35  * $Id $
36  *
37  * Changes
38  * -------
39  * 27-Mar-2003 : Version 1 (DG);
40  * 18-Aug-2003 : Implemented Cloneable (DG);
41  * 03-Mar-2005 : Implemented PublicCloneable (DG);
42  *
43  */
44
45 package org.jfree.data.general;
46
47 import java.io.Serializable JavaDoc;
48
49 import org.jfree.util.ObjectUtilities;
50 import org.jfree.util.PublicCloneable;
51
52 /**
53  * A dataset that stores a single value. This class provides a default
54  * implementation of the {@link ValueDataset} interface.
55  */
56 public class DefaultValueDataset extends AbstractDataset
57                                  implements ValueDataset,
58                                             Cloneable JavaDoc, PublicCloneable,
59                                             Serializable JavaDoc {
60
61     /** For serialization. */
62     private static final long serialVersionUID = 8137521217249294891L;
63     
64     /** The value. */
65     private Number JavaDoc value;
66
67     /**
68      * Constructs a new dataset, initially empty.
69      */
70     public DefaultValueDataset() {
71         this(null);
72     }
73     
74     /**
75      * Creates a new dataset.
76      *
77      * @param value the value.
78      */
79     public DefaultValueDataset(double value) {
80         this(new Double JavaDoc(value));
81     }
82
83     /**
84      * Creates a new dataset.
85      *
86      * @param value the initial value.
87      */
88     public DefaultValueDataset(Number JavaDoc value) {
89         this.value = value;
90     }
91
92     /**
93      * Returns the value.
94      *
95      * @return The value (possibly <code>null</code>).
96      */
97     public Number JavaDoc getValue() {
98         return this.value;
99     }
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 JavaDoc 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.
116      *
117      * @return A boolean.
118      */
119     public boolean equals(Object JavaDoc obj) {
120
121         if (obj == null) {
122             return false;
123         }
124
125         if (obj == this) {
126             return true;
127         }
128
129         if (obj instanceof ValueDataset) {
130             ValueDataset vd = (ValueDataset) obj;
131             return ObjectUtilities.equal(this.value, vd.getValue());
132         }
133
134         return false;
135     }
136
137     /**
138      * Returns a hash code.
139      *
140      * @return A hash code.
141      */
142     public int hashCode() {
143         return (this.value != null ? this.value.hashCode() : 0);
144     }
145     
146 }
147
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