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 implements
060: ValueDataset, Cloneable, PublicCloneable, Serializable {
061:
062: /** For serialization. */
063: private static final long serialVersionUID = 8137521217249294891L;
064:
065: /** The value. */
066: private Number value;
067:
068: /**
069: * Constructs a new dataset, initially empty.
070: */
071: public DefaultValueDataset() {
072: this (null);
073: }
074:
075: /**
076: * Creates a new dataset with the specified value.
077: *
078: * @param value the value.
079: */
080: public DefaultValueDataset(double value) {
081: this (new Double(value));
082: }
083:
084: /**
085: * Creates a new dataset with the specified value.
086: *
087: * @param value the initial value (<code>null</code> permitted).
088: */
089: public DefaultValueDataset(Number value) {
090: super ();
091: this .value = value;
092: }
093:
094: /**
095: * Returns the value.
096: *
097: * @return The value (possibly <code>null</code>).
098: */
099: public Number getValue() {
100: return this .value;
101: }
102:
103: /**
104: * Sets the value and sends a {@link DatasetChangeEvent} to all registered
105: * listeners.
106: *
107: * @param value the new value (<code>null</code> permitted).
108: */
109: public void setValue(Number value) {
110: this .value = value;
111: notifyListeners(new DatasetChangeEvent(this , this ));
112: }
113:
114: /**
115: * Tests this dataset 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 ValueDataset) {
126: ValueDataset vd = (ValueDataset) obj;
127: return ObjectUtilities.equal(this .value, vd.getValue());
128: }
129: return false;
130: }
131:
132: /**
133: * Returns a hash code.
134: *
135: * @return A hash code.
136: */
137: public int hashCode() {
138: return (this .value != null ? this .value.hashCode() : 0);
139: }
140:
141: }
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