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 * CategoryAnchor.java
029 * -------------------
030 * (C) Copyright 2003-present, by David Gilbert.
031 *
032 * Original Author:  David Gilbert;
033 * Contributor(s):   -;
034 *
035 */
036
037package org.jfree.chart.axis;
038
039import java.io.ObjectStreamException;
040import java.io.Serializable;
041
042/**
043 * Used to indicate one of three positions within a category:
044 * {@code START}, {@code MIDDLE} and {@code END}.
045 */
046public final class CategoryAnchor implements Serializable {
047
048    /** For serialization. */
049    private static final long serialVersionUID = -2604142742210173810L;
050
051    /** Start of period. */
052    public static final CategoryAnchor START
053        = new CategoryAnchor("CategoryAnchor.START");
054
055    /** Middle of period. */
056    public static final CategoryAnchor MIDDLE
057        = new CategoryAnchor("CategoryAnchor.MIDDLE");
058
059    /** End of period. */
060    public static final CategoryAnchor END
061        = new CategoryAnchor("CategoryAnchor.END");
062
063    /** The name. */
064    private final String name;
065
066    /**
067     * Private constructor.
068     *
069     * @param name  the name.
070     */
071    private CategoryAnchor(String name) {
072        this.name = name;
073    }
074
075    /**
076     * Returns a string representing the object.
077     *
078     * @return The string.
079     */
080    @Override
081    public String toString() {
082        return this.name;
083    }
084
085    /**
086     * Returns {@code true} if this object is equal to the specified
087     * object, and {@code false} otherwise.
088     *
089     * @param obj  the other object.
090     *
091     * @return A boolean.
092     */
093    @Override
094    public boolean equals(Object obj) {
095        if (this == obj) {
096            return true;
097        }
098        if (!(obj instanceof CategoryAnchor)) {
099            return false;
100        }
101        CategoryAnchor position = (CategoryAnchor) obj;
102        if (!this.name.equals(position.toString())) {
103            return false;
104        }
105        return true;
106    }
107
108    /**
109     * Ensures that serialization returns the unique instances.
110     *
111     * @return The object.
112     *
113     * @throws ObjectStreamException if there is a problem.
114     */
115    private Object readResolve() throws ObjectStreamException {
116        if (this.equals(CategoryAnchor.START)) {
117            return CategoryAnchor.START;
118        }
119        else if (this.equals(CategoryAnchor.MIDDLE)) {
120            return CategoryAnchor.MIDDLE;
121        }
122        else if (this.equals(CategoryAnchor.END)) {
123            return CategoryAnchor.END;
124        }
125        return null;
126    }
127
128}