001/* ========================================================================
002 * JCommon : a free general purpose class library for the Java(tm) platform
003 * ========================================================================
004 *
005 * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
006 * 
007 * Project Info:  http://www.jfree.org/jcommon/index.html
008 *
009 * This library is free software; you can redistribute it and/or modify it 
010 * under the terms of the GNU Lesser General Public License as published by 
011 * the Free Software Foundation; either version 2.1 of the License, or 
012 * (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but 
015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
017 * License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this library; if not, write to the Free Software
021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
022 * USA.  
023 *
024 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
025 * in the United States and other countries.]
026 * 
027 * --------------
028 * SortOrder.java
029 * --------------
030 * (C) Copyright 2003, 2004, by Object Refinery Limited.
031 *
032 * Original Author:  David Gilbert (for Object Refinery Limited);
033 * Contributor(s):   -;
034 *
035 * $Id: SortOrder.java,v 1.6 2005/10/18 13:24:19 mungady Exp $
036 *
037 * Changes:
038 * --------
039 * 05-Mar-2003 : Version 1 (DG);
040 * 13-Mar-2003 : Implemented Serializable (DG);
041 * 27-Aug-2003 : Moved from JFreeChart --> JCommon (DG);
042 * 29-Jul-2004 : Fixed error in readResolve() method (DG);
043 * 
044 */
045
046package org.jfree.util;
047
048import java.io.ObjectStreamException;
049import java.io.Serializable;
050
051/**
052 * Defines tokens used to indicate sorting order (ascending or descending).
053 *
054 * @author David Gilbert
055 */
056public final class SortOrder implements Serializable {
057
058    /** For serialization. */
059    private static final long serialVersionUID = -2124469847758108312L;
060    
061    /** Ascending order. */
062    public static final SortOrder ASCENDING 
063        = new SortOrder("SortOrder.ASCENDING");
064
065    /** Descending order. */
066    public static final SortOrder DESCENDING 
067        = new SortOrder("SortOrder.DESCENDING");
068
069    /** The name. */
070    private String name;
071
072    /**
073     * Private constructor.
074     *
075     * @param name  the name.
076     */
077    private SortOrder(final String name) {
078        this.name = name;
079    }
080
081    /**
082     * Returns a string representing the object.
083     *
084     * @return The string.
085     */
086    public String toString() {
087        return this.name;
088    }
089
090    /**
091     * Returns <code>true</code> if this object is equal to the specified 
092     * object, and <code>false</code> otherwise.
093     *
094     * @param obj  the other object.
095     *
096     * @return A boolean.
097     */
098    public boolean equals(final Object obj) {
099
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}