/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.io.comparator;
import java.io.Serializable;
import java.util.Comparator;
/**
* Reverses the result of comparing two objects using
* the delegate {@link Comparator}.
*
* @version $Revision: 609243 $ $Date: 2008-01-06 00:30:42 +0000 (Sun, 06 Jan 2008) $
* @since Commons IO 1.4
*/
class ReverseComparator implements Comparator, Serializable {
private final Comparator delegate;
/**
* Construct an instance with the sepecified delegate {@link Comparator}.
*
* @param delegate The comparator to delegate to
*/
public ReverseComparator(Comparator delegate) {
if (delegate == null) {
throw new IllegalArgumentException("Delegate comparator is missing");
}
this.delegate = delegate;
}
/**
* Compare using the delegate Comparator, but reversing the result.
*
* @param obj1 The first object to compare
* @param obj2 The second object to compare
* @return the result from the delegate {@link Comparator#compare(Object, Object)}
* reversing the value (i.e. positive becomes negative and vice versa)
*/
public int compare(Object obj1, Object obj2) {
return delegate.compare(obj2, obj1); // parameters switched round
}
}