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 }