Source for org.jfree.data.general.DefaultValueDataset

   1: /* ===========================================================
   2:  * JFreeChart : a free chart library for the Java(tm) platform
   3:  * ===========================================================
   4:  *
   5:  * (C) Copyright 2000-2007, 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 2003-2007, 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:  * ------------- JFREECHART 1.0.x ---------------------------------------------
  43:  * 30-Jan-2007 : Added explicit super() call in constructor (for clarity) (DG);
  44:  * 
  45:  */
  46: 
  47: package org.jfree.data.general;
  48: 
  49: import java.io.Serializable;
  50: 
  51: import org.jfree.util.ObjectUtilities;
  52: import org.jfree.util.PublicCloneable;
  53: 
  54: /**
  55:  * A dataset that stores a single value (that is possibly <code>null</code>).  
  56:  * This class provides a default implementation of the {@link ValueDataset} 
  57:  * interface.
  58:  */
  59: public class DefaultValueDataset extends AbstractDataset
  60:                                  implements ValueDataset, 
  61:                                             Cloneable, PublicCloneable,
  62:                                             Serializable {
  63: 
  64:     /** For serialization. */
  65:     private static final long serialVersionUID = 8137521217249294891L;
  66:     
  67:     /** The value. */
  68:     private Number value;
  69: 
  70:     /**
  71:      * Constructs a new dataset, initially empty.
  72:      */
  73:     public DefaultValueDataset() {
  74:         this(null);
  75:     }
  76:     
  77:     /**
  78:      * Creates a new dataset with the specified value.
  79:      * 
  80:      * @param value  the value.
  81:      */
  82:     public DefaultValueDataset(double value) {
  83:         this(new Double(value));
  84:     }
  85: 
  86:     /**
  87:      * Creates a new dataset with the specified value.
  88:      *
  89:      * @param value  the initial value (<code>null</code> permitted).
  90:      */
  91:     public DefaultValueDataset(Number value) {
  92:         super();
  93:         this.value = value;
  94:     }
  95: 
  96:     /**
  97:      * Returns the value.
  98:      *
  99:      * @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: }