Source for org.jfree.data.general.DefaultValueDataset

   1: /* ===========================================================
   2:  * JFreeChart : a free chart library for the Java(tm) platform
   3:  * ===========================================================
   4:  *
   5:  * (C) Copyright 2000-2005, 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;
  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, PublicCloneable,
  59:                                             Serializable {
  60: 
  61:     /** For serialization. */
  62:     private static final long serialVersionUID = 8137521217249294891L;
  63:     
  64:     /** The value. */
  65:     private Number 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(value));
  81:     }
  82: 
  83:     /**
  84:      * Creates a new dataset.
  85:      *
  86:      * @param value  the initial value.
  87:      */
  88:     public DefaultValueDataset(Number 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 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 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 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: }