001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-present, by David Gilbert and Contributors.
006 *
007 * Project Info:  http://www.jfree.org/jfreechart/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 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
025 * Other names may be trademarks of their respective owners.]
026 *
027 * ----------------
028 * DomainOrder.java
029 * ----------------
030 * (C) Copyright 2004-present, by David Gilbert.
031 *
032 * Original Author:  David Gilbert;
033 * Contributor(s):   -;
034 *
035 */
036
037package org.jfree.data;
038
039import java.io.ObjectStreamException;
040import java.io.Serializable;
041
042/**
043 * Used to indicate sorting order if any (ascending, descending or none).
044 */
045public final class DomainOrder implements Serializable {
046
047    /** For serialization. */
048    private static final long serialVersionUID = 4902774943512072627L;
049
050    /** No order. */
051    public static final DomainOrder NONE = new DomainOrder("DomainOrder.NONE");
052
053    /** Ascending order. */
054    public static final DomainOrder ASCENDING
055        = new DomainOrder("DomainOrder.ASCENDING");
056
057    /** Descending order. */
058    public static final DomainOrder DESCENDING
059        = new DomainOrder("DomainOrder.DESCENDING");
060
061    /** The name. */
062    private String name;
063
064    /**
065     * Private constructor.
066     *
067     * @param name  the name.
068     */
069    private DomainOrder(String name) {
070        this.name = name;
071    }
072
073    /**
074     * Returns a string representing the object.
075     *
076     * @return The string.
077     */
078    @Override
079    public String toString() {
080        return this.name;
081    }
082
083    /**
084     * Returns {@code true} if this object is equal to the specified
085     * object, and {@code false} otherwise.
086     *
087     * @param obj  the other object.
088     *
089     * @return A boolean.
090     */
091    @Override
092    public boolean equals(Object obj) {
093        if (this == obj) {
094            return true;
095        }
096        if (!(obj instanceof DomainOrder)) {
097            return false;
098        }
099        DomainOrder that = (DomainOrder) obj;
100        if (!this.name.equals(that.toString())) {
101            return false;
102        }
103        return true;
104    }
105
106    /**
107     * Returns a hash code value for the object.
108     *
109     * @return The hashcode
110     */
111    @Override
112    public int hashCode() {
113        return this.name.hashCode();
114    }
115
116    /**
117     * Ensures that serialization returns the unique instances.
118     *
119     * @return The object.
120     *
121     * @throws ObjectStreamException if there is a problem.
122     */
123    private Object readResolve() throws ObjectStreamException {
124        if (this.equals(DomainOrder.ASCENDING)) {
125            return DomainOrder.ASCENDING;
126        }
127        else if (this.equals(DomainOrder.DESCENDING)) {
128            return DomainOrder.DESCENDING;
129        }
130        else if (this.equals(DomainOrder.NONE)) {
131            return DomainOrder.NONE;
132        }
133        return null;
134    }
135
136}