Commons Collections example source code file (TestReverseComparator.java)

This example Commons Collections source code file (TestReverseComparator.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

bytearrayoutputstream, bytearrayoutputstream, comparablecomparator, comparator, comparator, integer, integer, io, list, object, objectinputstream, objectinputstream, objectoutputstream, reversecomparator, testreversecomparator, util

The Commons Collections TestReverseComparator.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.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.List;

import junit.framework.Test;
import junit.framework.TestSuite;

/**
 * Tests for ReverseComparator.
 * 
 * @version $Revision: 646780 $ $Date: 2008-04-10 13:48:07 +0100 (Thu, 10 Apr 2008) $
 * 
 * @author Unknown
 */
public class TestReverseComparator extends AbstractTestComparator {

    public TestReverseComparator(String testName) {
        super(testName);
    }

    public static Test suite() {
        return new TestSuite(TestReverseComparator.class);
    }

    /**
     * For the purposes of this test, return a 
     * ReverseComparator that wraps the java.util.Collections.reverseOrder()
     * Comparator.  The resulting comparator should
     * sort according to natural Order.  (Note: we wrap
     * a Comparator taken from the JDK so that we can
     * save a "canonical" form in CVS.
     * 
     * @return Comparator that returns "natural" order
     */
    public Comparator makeComparator() {
        return new ReverseComparator(Collections.reverseOrder());
    }

    public List getComparableObjectsOrdered() {
        List list = new LinkedList();
        list.add(new Integer(1));
        list.add(new Integer(2));
        list.add(new Integer(3));
        list.add(new Integer(4));
        list.add(new Integer(5));
        return list;
    }

    /** 
     * Override this inherited test since Collections.reverseOrder
     * doesn't adhere to the "soft" Comparator contract, and we've
     * already "cannonized" the comparator returned by makeComparator.
     */
    public void testSerializeDeserializeThenCompare() throws Exception {
        Comparator comp = new ReverseComparator(new ComparableComparator());

        ByteArrayOutputStream buffer = new ByteArrayOutputStream();
        ObjectOutputStream out = new ObjectOutputStream(buffer);
        out.writeObject(comp);
        out.close();
            
        ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(buffer.toByteArray()));
        Object dest = in.readObject();
        in.close();
        assertEquals("obj != deserialize(serialize(obj))",comp,dest);
    }

}