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    
046    package org.jfree.util;
047    
048    import java.io.ObjectStreamException;
049    import java.io.Serializable;
050    
051    /**
052     * Defines tokens used to indicate sorting order (ascending or descending).
053     *
054     * @author David Gilbert
055     */
056    public 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    }