    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     * ClassComparator.java
    029     * --------------------
    030     * (C)opyright 2003, 2004, by Thomas Morgner and Contributors.
    031     *
    032     * Original Author:  Thomas Morgner (taquera@sherito.org);
    033     * Contributor(s):   David Gilbert (for Object Refinery Limited);
    034     *
    035     * $Id: ClassComparator.java,v 1.5 2005/11/08 14:22:04 mungady Exp $
    036     *
    037     * Changes
    038     * -------
    039     * 02-May-2003 : Initial version
    040     */
    041    package org.jfree.xml.factory.objects;
    042
    043    import java.io.Serializable;
    044    import java.util.Comparator;
    045
    046    /**
    047     * The class comparator can be used to compare and sort classes and their
    048     * superclasses. The comparator is not able to compare classes which have
    049     * no relation...
    050     *
    051     * @author Thomas Morgner
    052     * @deprecated Moved to org.jfree.util
    053     */
    054    public class ClassComparator implements Comparator, Serializable {
    055
    056        /**
    057         * Defaultconstructor.
    058         */
    059        public ClassComparator() {
    060            super();
    061        }
    062
    063        /**
    064         * Compares its two arguments for order.  Returns a negative integer,
    065         * zero, or a positive integer as the first argument is less than, equal
    066         * to, or greater than the second.<p>
    067         * <P>
    068         * Note: throws ClassCastException if the arguments' types prevent them from
    069         * being compared by this Comparator.
    070         * And IllegalArgumentException if the classes share no relation.
    071         *
    072         * The implementor must ensure that <tt>sgn(compare(x, y)) ==
    073         * -sgn(compare(y, x))</tt> for all <tt>x</tt> and <tt>y</tt>.  (This
    074         * implies that <tt>compare(x, y)</tt> must throw an exception if and only
    075         * if <tt>compare(y, x)</tt> throws an exception.)<p>
    076         *
    077         * The implementor must also ensure that the relation is transitive:
    078         * <tt>((compare(x, y)&gt;0) &amp;&amp; (compare(y, z)&gt;0))</tt> implies
    079         * <tt>compare(x, z)&gt;0</tt>.<p>
    080         *
    081         * Finally, the implementer must ensure that <tt>compare(x, y)==0</tt>
    082         * implies that <tt>sgn(compare(x, z))==sgn(compare(y, z))</tt> for all
    083         * <tt>z</tt>.<p>
    084         *
    085         * It is generally the case, but <i>not</i> strictly required that
    086         * <tt>(compare(x, y)==0) == (x.equals(y))</tt>.  Generally speaking,
    087         * any comparator that violates this condition should clearly indicate
    088         * this fact.  The recommended language is "Note: this comparator
    089         * imposes orderings that are inconsistent with equals."
    090         *
    091         * @param o1 the first object to be compared.
    092         * @param o2 the second object to be compared.
    093         * @return a negative integer, zero, or a positive integer as the
    094         *         first argument is less than, equal to, or greater than the
    095         *         second.
    096         */
    097        public int compare(final Object o1, final Object o2) {
    098            final Class c1 = (Class) o1;
    099            final Class c2 = (Class) o2;
    100            if (c1.equals(o2)) {
    101                return 0;
    102            }
    103            if (c1.isAssignableFrom(c2)) {
    104                return -1;
    105            }
    106            else {
    107                if (!c2.isAssignableFrom(c2)) {
    108                    throw new IllegalArgumentException("The classes share no relation");
    109                }
    110                return 1;
    111            }
    112        }
    113
    114        /**
    115         * Checks, whether the given classes are comparable. This method will
    116         * return true, if one of the classes is assignable from the other class.
    117         *
    118         * @param c1 the first class to compare
    119         * @param c2 the second class to compare
    120         * @return true, if the classes share a direct relation, false otherwise.
    121         */
    122        public boolean isComparable(final Class c1, final Class c2) {
    123            return (c1.isAssignableFrom(c2) || c2.isAssignableFrom(c1));
    124        }
    125    }