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Commons Collections example source code file (TestFixedOrderComparator.java)

This example Commons Collections source code file (TestFixedOrderComparator.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

fixedordercomparator, fixedordercomparator, illegalargumentexception, minneapolis, minneapolis, new, new, object, should, string, string, tokyo, unsupportedoperationexception, util, york

The Commons Collections TestFixedOrderComparator.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.Arrays;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.List;
import java.util.Random;

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

/**
 * Test class for FixedOrderComparator.
 * 
 * @version $Revision: 646780 $ $Date: 2008-04-10 13:48:07 +0100 (Thu, 10 Apr 2008) $
 * 
 * @author David Leppik 
 * @author Stephen Colebourne
 */
public class TestFixedOrderComparator extends TestCase {


    /**
     * Top cities of the world, by population including metro areas.
     */
    public static final String topCities[] = new String[] {
        "Tokyo",
        "Mexico City",
        "Mumbai",
        "Sao Paulo",
        "New York",
        "Shanghai",
        "Lagos",
        "Los Angeles",
        "Calcutta",
        "Buenos Aires"
    };

    //
    // Initialization and busywork
    //

    public TestFixedOrderComparator(String name) {
        super(name);
    }

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

    public static void main(String args[]) { 
        junit.textui.TestRunner.run(suite());
    }

    //
    // Set up and tear down
    //



    //
    // The tests
    //

    /** 
     * Tests that the constructor plus add method compares items properly. 
     */
    public void testConstructorPlusAdd() {
        FixedOrderComparator comparator = new FixedOrderComparator();
        for (int i = 0; i < topCities.length; i++) {
            comparator.add(topCities[i]);
        }
        String[] keys = (String[]) topCities.clone();
        assertComparatorYieldsOrder(keys, comparator);
    }

    /** 
     * Tests that the array constructor compares items properly. 
     */
    public void testArrayConstructor() {
        String[] keys = (String[]) topCities.clone();
        String[] topCitiesForTest = (String[]) topCities.clone();
        FixedOrderComparator comparator = new FixedOrderComparator(topCitiesForTest);
        assertComparatorYieldsOrder(keys, comparator);
        // test that changing input after constructor has no effect
        topCitiesForTest[0] = "Brighton";
        assertComparatorYieldsOrder(keys, comparator);
    }

    /**
     * Tests the list constructor. 
     */
    public void testListConstructor() {
        String[] keys = (String[]) topCities.clone();
        List topCitiesForTest = new LinkedList(Arrays.asList(topCities));
        FixedOrderComparator comparator = new FixedOrderComparator(topCitiesForTest);
        assertComparatorYieldsOrder(keys, comparator);
        // test that changing input after constructor has no effect
        topCitiesForTest.set(0, "Brighton");
        assertComparatorYieldsOrder(keys, comparator);
    }

    /**
     * Tests addAsEqual method.
     */
    public void testAddAsEqual() {
        FixedOrderComparator comparator = new FixedOrderComparator(topCities);
        comparator.addAsEqual("New York", "Minneapolis");
        assertEquals(0, comparator.compare("New York", "Minneapolis"));
        assertEquals(-1, comparator.compare("Tokyo", "Minneapolis"));
        assertEquals(1, comparator.compare("Shanghai", "Minneapolis"));
    }

    /** 
     * Tests whether or not updates are disabled after a comparison is made.
     */
    public void testLock() {
        FixedOrderComparator comparator = new FixedOrderComparator(topCities);
        assertEquals(false, comparator.isLocked());
        comparator.compare("New York", "Tokyo");
        assertEquals(true, comparator.isLocked());
        try {
            comparator.add("Minneapolis");
            fail("Should have thrown an UnsupportedOperationException");
        } catch (UnsupportedOperationException e) {
            // success -- ignore
        }

        try {
            comparator.addAsEqual("New York", "Minneapolis");
            fail("Should have thrown an UnsupportedOperationException");
        } catch (UnsupportedOperationException e) {
            // success -- ignore
        }
    }

    public void testUnknownObjectBehavior() {
        FixedOrderComparator comparator = new FixedOrderComparator(topCities);
        try {
            comparator.compare("New York", "Minneapolis");
            fail("Should have thrown a IllegalArgumentException");
        } catch (IllegalArgumentException e) {
            // success-- ignore
        }
        try {
            comparator.compare("Minneapolis", "New York");
            fail("Should have thrown a IllegalArgumentException");
        } catch (IllegalArgumentException e) {
            // success-- ignore
        }
        assertEquals(FixedOrderComparator.UNKNOWN_THROW_EXCEPTION, comparator.getUnknownObjectBehavior());

        comparator = new FixedOrderComparator(topCities);
        comparator.setUnknownObjectBehavior(FixedOrderComparator.UNKNOWN_BEFORE);
        assertEquals(FixedOrderComparator.UNKNOWN_BEFORE, comparator.getUnknownObjectBehavior());
        LinkedList keys = new LinkedList(Arrays.asList(topCities));
        keys.addFirst("Minneapolis");
        assertComparatorYieldsOrder(keys.toArray(new String[0]), comparator);
        
        assertEquals(-1, comparator.compare("Minneapolis", "New York"));
        assertEquals( 1, comparator.compare("New York", "Minneapolis"));
        assertEquals( 0, comparator.compare("Minneapolis", "St Paul"));

        comparator = new FixedOrderComparator(topCities);
        comparator.setUnknownObjectBehavior(FixedOrderComparator.UNKNOWN_AFTER);
        keys = new LinkedList(Arrays.asList(topCities));
        keys.add("Minneapolis");
        assertComparatorYieldsOrder(keys.toArray(new String[0]), comparator);
        
        assertEquals( 1, comparator.compare("Minneapolis", "New York"));
        assertEquals(-1, comparator.compare("New York", "Minneapolis"));
        assertEquals( 0, comparator.compare("Minneapolis", "St Paul"));
        
    }
    
    //
    // Helper methods
    //
    
    /** Shuffles the keys and asserts that the comparator sorts them back to
     * their original order.
     */
    private void assertComparatorYieldsOrder(Object[] orderedObjects, 
                                             Comparator comparator) {
        Object[] keys = (Object[]) orderedObjects.clone();
        
        // shuffle until the order changes.  It's extremely rare that
        // this requires more than one shuffle.

        boolean isInNewOrder = false;
        while (keys.length > 1 && isInNewOrder == false) {
            shuffle: {
                Random rand = new Random();
                for (int i = keys.length-1; i > 0; i--) {
                        Object swap = keys[i];
                        int j = rand.nextInt(i+1);
                        keys[i] = keys[j];
                        keys[j] = swap;     
                    }
            }
        
            testShuffle: {
                for (int i = 0; i < keys.length && !isInNewOrder; i++) {
                    if( !orderedObjects[i].equals(keys[i])) {
                        isInNewOrder = true;
                    }
                }
            }
        }
        
        // The real test:  sort and make sure they come out right.
        
        Arrays.sort(keys, comparator);

        for (int i = 0; i < orderedObjects.length; i++) {
            assertEquals(orderedObjects[i], keys[i]);
        }
    }
    
}

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