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Commons Collections example source code file (AbstractTestComparator.java)

This example Commons Collections source code file (AbstractTestComparator.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

abstracttestcomparator, abstracttestobject, comparator, comparator, io, ioexception, linkedlist, list, list, serializable, serializable, serialized, string, string, stringbuffer, util

The Commons Collections AbstractTestComparator.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.FileNotFoundException;
import java.io.IOException;
import java.io.Serializable;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.List;

import org.apache.commons.collections.AbstractTestObject;

/**
 * Abstract test class for testing the Comparator interface.
 * <p>
 * Concrete subclasses declare the comparator to be tested.
 * They also declare certain aspects of the tests.
 * 
 * @author Stephen Colebourne
 */
public abstract class AbstractTestComparator extends AbstractTestObject {

    /**
     * JUnit constructor.
     * 
     * @param testName  the test class name
     */
    public AbstractTestComparator(String testName) {
        super(testName);
    }

    //-----------------------------------------------------------------------
    /**
     * Implement this method to return the comparator to test.
     * 
     * @return the comparator to test
     */
    public abstract Comparator makeComparator();
    
    /**
     * Implement this method to return a list of sorted objects.
     * 
     * @return sorted objects
     */
    public abstract List getComparableObjectsOrdered();

    //-----------------------------------------------------------------------
    /**
     * Implements the abstract superclass method to return the comparator.
     * 
     * @return a full iterator
     */
    public Object makeObject() {
        return makeComparator();
    }

    /**
     * Overrides superclass to block tests.
     */
    public boolean supportsEmptyCollections() {
        return false;
    }

    /**
     * Overrides superclass to block tests.
     */
    public boolean supportsFullCollections() {
        return false;
    }

    /**
     * Overrides superclass to set the compatability to version 2
     * as there were no Comparators in version 1.x.
     */
    public String getCompatibilityVersion() {
        return "2";
    }

    //-----------------------------------------------------------------------
    /**
     * Reverse the list.
     */
    protected void reverseObjects(List list) {
        Collections.reverse(list);
    }

    /**
     * Randomize the list.
     */
    protected void randomizeObjects(List list) {
        Collections.shuffle(list);
    }

    /**
     * Sort the list.
     */
    protected void sortObjects(List list, Comparator comparator) {
        Collections.sort(list,comparator);

    }

    //-----------------------------------------------------------------------
    /**
     * Test sorting an empty list
     */
    public void testEmptyListSort() {
        List list = new LinkedList();
        sortObjects(list, makeComparator());

        List list2 = new LinkedList();
        
        assertTrue("Comparator cannot sort empty lists",
                   list2.equals(list));
    }

    /**
     * Test sorting a reversed list.
     */
    public void testReverseListSort() {
        Comparator comparator = makeComparator();

        List randomList = getComparableObjectsOrdered();
        reverseObjects(randomList);
        sortObjects(randomList,comparator);

        List orderedList = getComparableObjectsOrdered();

        assertTrue("Comparator did not reorder the List correctly",
                   orderedList.equals(randomList));

    }

    /**
     * Test sorting a random list.
     */
    public void testRandomListSort() {
        Comparator comparator = makeComparator();

        List randomList = getComparableObjectsOrdered();
        randomizeObjects(randomList);
        sortObjects(randomList,comparator);

        List orderedList = getComparableObjectsOrdered();

        /* debug 
        Iterator i = randomList.iterator();
        while (i.hasNext()) {
            System.out.println(i.next());
        }
        */

        assertTrue("Comparator did not reorder the List correctly",
                   orderedList.equals(randomList));

    }

    /**
     * Nearly all Comparators should be Serializable.
     */
    public void testComparatorIsSerializable() {
        Comparator comparator = makeComparator();
        assertTrue("This comparator should be Serializable.",
                   comparator instanceof Serializable);
    }

    public String getCanonicalComparatorName(Object object) {
        StringBuffer retval = new StringBuffer();
        retval.append("data/test/");
        String colName = object.getClass().getName();
        colName = colName.substring(colName.lastIndexOf(".")+1,colName.length());
        retval.append(colName);
        retval.append(".version");
        retval.append(getCompatibilityVersion());
        retval.append(".obj");
        return retval.toString();
    }

    /**
     * Compare the current serialized form of the Comparator
     * against the canonical version in CVS.
     */
    public void testComparatorCompatibility() throws IOException, ClassNotFoundException {
        if(!skipSerializedCanonicalTests()) {
            Comparator comparator = null;
    
            // test to make sure the canonical form has been preserved
            try {
                comparator = (Comparator) readExternalFormFromDisk(getCanonicalComparatorName(makeComparator()));
        	} catch (FileNotFoundException exception) {
    
                boolean autoCreateSerialized = false;
    
        	    if(autoCreateSerialized) {
    	          	comparator = makeComparator();
            		String fileName = getCanonicalComparatorName(comparator);
            		writeExternalFormToDisk((Serializable) comparator, fileName);
            		fail("Serialized form could not be found.  A serialized version " +
            		     "has now been written (and should be added to CVS): " + fileName);
                } else {
                    fail("The Serialized form could be located to test serialization " +
                        "compatibility: " + exception.getMessage());
                }
            }
    
            
            // make sure the canonical form produces the ordering we currently
            // expect
            List randomList = getComparableObjectsOrdered();
            reverseObjects(randomList);
            sortObjects(randomList,comparator);
    
            List orderedList = getComparableObjectsOrdered();
    
            assertTrue("Comparator did not reorder the List correctly",
                       orderedList.equals(randomList));
        }
    }

}

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