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Commons Collections example source code file (TransformingComparator.java)

This example Commons Collections source code file (TransformingComparator.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons Collections tags/keywords

comparablecomparator, comparator, comparator, object, object, transformer, transformer, transformingcomparator, transformingcomparator, util

The Commons Collections TransformingComparator.java source code

 *  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.collections.comparators;

import java.util.Comparator;

import org.apache.commons.collections.Transformer;

 * Decorates another Comparator with transformation behavior. That is, the
 * return value from the transform operation will be passed to the decorated
 * {@link Comparator#compare(Object,Object) compare} method.
 * @since Commons Collections 2.0 (?)
 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
 * @see org.apache.commons.collections.Transformer
 * @see org.apache.commons.collections.comparators.ComparableComparator
public class TransformingComparator implements Comparator {
    /** The decorated comparator. */
    protected Comparator decorated;
    /** The transformer being used. */    
    protected Transformer transformer;

     * Constructs an instance with the given Transformer and a 
     * {@link ComparableComparator ComparableComparator}.
     * @param transformer what will transform the arguments to <code>compare
    public TransformingComparator(Transformer transformer) {
        this(transformer, new ComparableComparator());

     * Constructs an instance with the given Transformer and Comparator.
     * @param transformer  what will transform the arguments to <code>compare
     * @param decorated  the decorated Comparator
    public TransformingComparator(Transformer transformer, Comparator decorated) {
        this.decorated = decorated;
        this.transformer = transformer;

     * Returns the result of comparing the values from the transform operation.
     * @param obj1  the first object to transform then compare
     * @param obj2  the second object to transform then compare
     * @return negative if obj1 is less, positive if greater, zero if equal
    public int compare(Object obj1, Object obj2) {
        Object value1 = this.transformer.transform(obj1);
        Object value2 = this.transformer.transform(obj2);
        return this.decorated.compare(value1, value2);


Other Commons Collections examples (source code examples)

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