Source for org.jfree.util.SortOrder

   1: /* ========================================================================
   2:  * JCommon : a free general purpose class 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/jcommon/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:  * SortOrder.java
  29:  * --------------
  30:  * (C) Copyright 2003, 2004, by Object Refinery Limited.
  31:  *
  32:  * Original Author:  David Gilbert (for Object Refinery Limited);
  33:  * Contributor(s):   -;
  34:  *
  35:  * $Id: SortOrder.java,v 1.6 2005/10/18 13:24:19 mungady Exp $
  36:  *
  37:  * Changes:
  38:  * --------
  39:  * 05-Mar-2003 : Version 1 (DG);
  40:  * 13-Mar-2003 : Implemented Serializable (DG);
  41:  * 27-Aug-2003 : Moved from JFreeChart --> JCommon (DG);
  42:  * 29-Jul-2004 : Fixed error in readResolve() method (DG);
  43:  * 
  44:  */
  45: 
  46: package org.jfree.util;
  47: 
  48: import java.io.ObjectStreamException;
  49: import java.io.Serializable;
  50: 
  51: /**
  52:  * Defines tokens used to indicate sorting order (ascending or descending).
  53:  *
  54:  * @author David Gilbert
  55:  */
  56: public final class SortOrder implements Serializable {
  57: 
  58:     /** For serialization. */
  59:     private static final long serialVersionUID = -2124469847758108312L;
  60:     
  61:     /** Ascending order. */
  62:     public static final SortOrder ASCENDING 
  63:         = new SortOrder("SortOrder.ASCENDING");
  64: 
  65:     /** Descending order. */
  66:     public static final SortOrder DESCENDING 
  67:         = new SortOrder("SortOrder.DESCENDING");
  68: 
  69:     /** The name. */
  70:     private String name;
  71: 
  72:     /**
  73:      * Private constructor.
  74:      *
  75:      * @param name  the name.
  76:      */
  77:     private SortOrder(final String name) {
  78:         this.name = name;
  79:     }
  80: 
  81:     /**
  82:      * Returns a string representing the object.
  83:      *
  84:      * @return The string.
  85:      */
  86:     public String toString() {
  87:         return this.name;
  88:     }
  89: 
  90:     /**
  91:      * Returns <code>true</code> if this object is equal to the specified 
  92:      * object, and <code>false</code> otherwise.
  93:      *
  94:      * @param obj  the other object.
  95:      *
  96:      * @return A boolean.
  97:      */
  98:     public boolean equals(final Object obj) {
  99: 
 100:         if (this == obj) {
 101:             return true;
 102:         }
 103:         if (!(obj instanceof SortOrder)) {
 104:             return false;
 105:         }
 106: 
 107:         final SortOrder that = (SortOrder) obj;
 108:         if (!this.name.equals(that.toString())) {
 109:             return false;
 110:         }
 111: 
 112:         return true;
 113:     }
 114:     
 115:     /**
 116:      * Returns a hash code value for the object.
 117:      *
 118:      * @return The hashcode
 119:      */
 120:     public int hashCode() {
 121:         return this.name.hashCode();
 122:     }
 123: 
 124:     /**
 125:      * Ensures that serialization returns the unique instances.
 126:      * 
 127:      * @return The object.
 128:      * 
 129:      * @throws ObjectStreamException if there is a problem.
 130:      */
 131:     private Object readResolve() throws ObjectStreamException {
 132:         if (this.equals(SortOrder.ASCENDING)) {
 133:             return SortOrder.ASCENDING;
 134:         }
 135:         else if (this.equals(SortOrder.DESCENDING)) {
 136:             return SortOrder.DESCENDING;
 137:         }
 138:         return null;
 139:     }
 140: }