HistogramType.java

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2011, by Object Refinery Limited and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
 * Other names may be trademarks of their respective owners.]
 *
 * ------------------
 * HistogramType.java
 * ------------------
 * (C) Copyright 2004-2008, by Object Refinery Limited and Contributors.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * Changes
 * -------
 * 05-Mar-2004 : Version 1 (DG);
 *
 */

package org.jfree.data.statistics;

import java.io.ObjectStreamException;
import java.io.Serializable;

/**
 * A class for creating constants to represent the histogram type.  See Bloch's
 * enum tip in 'Effective Java'.
 */
public class HistogramType implements Serializable {

    /** For serialization. */
    private static final long serialVersionUID = 2618927186251997727L;

    /** Frequency histogram. */
    public static final HistogramType FREQUENCY
        = new HistogramType("FREQUENCY");

    /** Relative frequency. */
    public static final HistogramType RELATIVE_FREQUENCY
        = new HistogramType("RELATIVE_FREQUENCY");

    /** Scale area to one. */
    public static final HistogramType SCALE_AREA_TO_1
        = new HistogramType("SCALE_AREA_TO_1");

    /** The type name. */
    private String name;

    /**
     * Creates a new type.
     *
     * @param name  the name.
     */
    private HistogramType(String name) {
        this.name = name;
    }

    /**
     * Returns a string representing the object.
     *
     * @return The string.
     */
    public String toString() {
        return this.name;
    }

    /**
     * Tests this type for equality with an arbitrary object.
     *
     * @param obj  the object to test against.
     *
     * @return A boolean.
     */
    public boolean equals(Object obj) {

        if (obj == null) {
            return false;
        }

        if (obj == this) {
            return true;
        }

        if (!(obj instanceof HistogramType)) {
            return false;
        }

        HistogramType t = (HistogramType) obj;
        if (!this.name.equals(t.name)) {
            return false;
        }

        return true;

    }

    /**
     * Returns a hash code value for the object.
     *
     * @return The hashcode
     */
    public int hashCode() {
        return this.name.hashCode();
    }

    /**
     * Ensures that serialization returns the unique instances.
     *
     * @return The object.
     *
     * @throws ObjectStreamException if there is a problem.
     */
    private Object readResolve() throws ObjectStreamException {
        if (this.equals(HistogramType.FREQUENCY)) {
            return HistogramType.FREQUENCY;
        }
        else if (this.equals(HistogramType.RELATIVE_FREQUENCY)) {
            return HistogramType.RELATIVE_FREQUENCY;
        }
        else if (this.equals(HistogramType.SCALE_AREA_TO_1)) {
            return HistogramType.SCALE_AREA_TO_1;
        }
        return null;
    }

}