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:  * Changes
  36:  * -------
  37:  * 27-Mar-2003 : Version 1 (DG);
  38:  * 18-Aug-2003 : Implemented Cloneable (DG);
  39:  * 03-Mar-2005 : Implemented PublicCloneable (DG);
  40:  * ------------- JFREECHART 1.0.x ---------------------------------------------
  41:  * 30-Jan-2007 : Added explicit super() call in constructor (for clarity) (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 (that is possibly <code>null</code>).  
  54:  * This class provides a default implementation of the {@link ValueDataset} 
  55:  * interface.
  56:  */
  57: public class DefaultValueDataset extends AbstractDataset
  58:                                  implements ValueDataset, 
  59:                                             Cloneable, PublicCloneable,
  60:                                             Serializable {
  61: 
  62:     /** For serialization. */
  63:     private static final long serialVersionUID = 8137521217249294891L;
  64:     
  65:     /** The value. */
  66:     private Number value;
  67: 
  68:     /**
  69:      * Constructs a new dataset, initially empty.
  70:      */
  71:     public DefaultValueDataset() {
  72:         this(null);
  73:     }
  74:     
  75:     /**
  76:      * Creates a new dataset with the specified value.
  77:      * 
  78:      * @param value  the value.
  79:      */
  80:     public DefaultValueDataset(double value) {
  81:         this(new Double(value));
  82:     }
  83: 
  84:     /**
  85:      * Creates a new dataset with the specified value.
  86:      *
  87:      * @param value  the initial value (<code>null</code> permitted).
  88:      */
  89:     public DefaultValueDataset(Number value) {
  90:         super();
  91:         this.value = value;
  92:     }
  93: 
  94:     /**
  95:      * Returns the value.
  96:      *
  97:      * @return The value (possibly <code>null</code>).
  98:      */
  99:     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: }