ReverseComparator.java

/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.utility;

import java.io.Serializable;
import java.util.Comparator;

/**
 * This comparator will reverse the order of the specified comparator.
 * If the comparator is null, the natural ordering of the objects will be used.
 */
public class ReverseComparator
    implements Comparator, Serializable
{
    private final Comparator comparator;

    /**
     * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
     */
    public ReverseComparator() {
        this(null);
    }

    /**
     * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
     */
    public ReverseComparator(Comparator comparator) {
        super();
        this.comparator = comparator;
    }

    /**
     * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
     */
    public int compare(Object o1, Object o2) {
        if (this.comparator == null) {
            return ((Comparable) o2).compareTo(o1);
        }
        return this.comparator.compare(o2, o1);
    }

}