Source for org.jfree.data.DefaultKeyedValue

   1: /* ===========================================================
   2:  * JFreeChart : a free chart library for the Java(tm) platform
   3:  * ===========================================================
   4:  *
   5:  * (C) Copyright 2000-2008, 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:  * DefaultKeyedValue.java
  29:  * ----------------------
  30:  * (C) Copyright 2002-2008, by Object Refinery Limited.
  31:  *
  32:  * Original Author:  David Gilbert (for Object Refinery Limited);
  33:  * Contributor(s):   -;
  34:  *
  35:  * Changes:
  36:  * --------
  37:  * 31-Oct-2002 : Version 1 (DG);
  38:  * 13-Mar-2003 : Added equals() method, and implemented Serializable (DG);
  39:  * 18-Aug-2003 : Implemented Cloneable (DG);
  40:  * 18-Aug-2004 : Moved from org.jfree.data --> org.jfree.data.base (DG);
  41:  * 15-Sep-2004 : Added PublicCloneable interface (DG);
  42:  * ------------- JFREECHART 1.0.x ---------------------------------------------
  43:  * 11-Jun-2007 : Added toString() method to help with debugging (DG);
  44:  * 15-Feb-2008 : Prevent null key (DG);
  45:  * 07-Apr-2008 : Removed to-do item (DG);
  46:  * 
  47:  */
  48: 
  49: package org.jfree.data;
  50: 
  51: import java.io.Serializable;
  52: 
  53: import org.jfree.util.PublicCloneable;
  54: 
  55: /**
  56:  * A (key, value) pair.  This class provides a default implementation 
  57:  * of the {@link KeyedValue} interface.
  58:  */
  59: public class DefaultKeyedValue implements KeyedValue, 
  60:                                           Cloneable, PublicCloneable, 
  61:                                           Serializable {
  62: 
  63:     /** For serialization. */
  64:     private static final long serialVersionUID = -7388924517460437712L;
  65:     
  66:     /** The key. */
  67:     private Comparable key;
  68: 
  69:     /** The value. */
  70:     private Number value;
  71: 
  72:     /**
  73:      * Creates a new (key, value) item.
  74:      *
  75:      * @param key  the key (should be immutable, <code>null</code> not 
  76:      *         permitted).
  77:      * @param value  the value (<code>null</code> permitted).
  78:      */
  79:     public DefaultKeyedValue(Comparable key, Number value) {
  80:         if (key == null) {
  81:             throw new IllegalArgumentException("Null 'key' argument.");
  82:         }
  83:         this.key = key;
  84:         this.value = value;
  85:     }
  86: 
  87:     /**
  88:      * Returns the key.
  89:      *
  90:      * @return The key (never <code>null</code>).
  91:      */
  92:     public Comparable getKey() {
  93:         return this.key;
  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.
 107:      *
 108:      * @param value  the value (<code>null</code> permitted).
 109:      */
 110:     public synchronized void setValue(Number value) {
 111:         this.value = value;
 112:     }
 113: 
 114:     /**
 115:      * Tests this key-value pair 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 DefaultKeyedValue)) {
 126:             return false;
 127:         }
 128:         DefaultKeyedValue that = (DefaultKeyedValue) obj;
 129:         
 130:         if (!this.key.equals(that.key)) {
 131:             return false;
 132:         }
 133:         if (this.value != null 
 134:                 ? !this.value.equals(that.value) : that.value != null) {
 135:             return false;
 136:         }
 137:         return true;
 138:     }
 139: 
 140:     /**
 141:      * Returns a hash code.
 142:      * 
 143:      * @return A hash code.
 144:      */
 145:     public int hashCode() {
 146:         int result;
 147:         result = (this.key != null ? this.key.hashCode() : 0);
 148:         result = 29 * result + (this.value != null ? this.value.hashCode() : 0);
 149:         return result;
 150:     }
 151: 
 152:     /**
 153:      * Returns a clone.  It is assumed that both the key and value are 
 154:      * immutable objects, so only the references are cloned, not the objects 
 155:      * themselves.
 156:      * 
 157:      * @return A clone.
 158:      * 
 159:      * @throws CloneNotSupportedException Not thrown by this class, but 
 160:      *         subclasses (if any) might.
 161:      */
 162:     public Object clone() throws CloneNotSupportedException {
 163:         DefaultKeyedValue clone = (DefaultKeyedValue) super.clone();
 164:         return clone;
 165:     }
 166:     
 167:     /** 
 168:      * Returns a string representing this instance, primarily useful for 
 169:      * debugging.
 170:      * 
 171:      * @return A string.
 172:      */
 173:     public String toString() {
 174:         return "(" + this.key.toString() + ", " + this.value.toString() + ")";
 175:     }
 176: 
 177: }