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Commons Collections example source code file (TestFilterListIterator.java)

This example Commons Collections source code file (TestFilterListIterator.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

arraylist, arraylist, filterlistiterator, filterlistiterator, integer, listiterator, listiterator, object, predicate, predicate, random, stringbuffer, testcase, testfilterlistiterator, util

The Commons Collections TestFilterListIterator.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.iterators;

import java.util.ArrayList;
import java.util.List;
import java.util.ListIterator;
import java.util.Random;

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

import org.apache.commons.collections.Predicate;

/**
 * Tests the FilterListIterator class.
 * 
 * @version $Revision: 646780 $ $Date: 2008-04-10 13:48:07 +0100 (Thu, 10 Apr 2008) $
 * 
 * @author Rodney Waldhoff
 */
public class TestFilterListIterator extends TestCase {
    public TestFilterListIterator(String testName) {
        super(testName);
    }

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

    public static void main(String args[]) {
        String[] testCaseName = { TestFilterListIterator.class.getName() };
        junit.textui.TestRunner.main(testCaseName);
    }

    private ArrayList list = null;
    private ArrayList odds = null;
    private ArrayList evens = null;
    private ArrayList threes = null;
    private ArrayList fours = null;
    private ArrayList sixes = null;
    private Predicate truePred = null;
    private Predicate falsePred = null;
    private Predicate evenPred = null;
    private Predicate oddPred = null;
    private Predicate threePred = null;
    private Predicate fourPred = null;
    private Random random = new Random();

    public void setUp() {
        list = new ArrayList();
        odds = new ArrayList();
        evens = new ArrayList();
        threes = new ArrayList();
        fours = new ArrayList();
        sixes = new ArrayList();
        for(int i=0;i<20;i++) {
            list.add(new Integer(i));
            if(i%2 == 0) { evens.add(new Integer(i)); }
            if(i%2 == 1) { odds.add(new Integer(i)); }
            if(i%3 == 0) { threes.add(new Integer(i)); }
            if(i%4 == 0) { fours.add(new Integer(i)); }
            if(i%6 == 0) { sixes.add(new Integer(i)); }
        }

        truePred = new Predicate() {
            public boolean evaluate(Object x) { 
                return true;
            }
        };

        falsePred = new Predicate() {
            public boolean evaluate(Object x) { 
                return true;
            }
        };

        evenPred = new Predicate() {
            public boolean evaluate(Object x) { 
                return (((Integer)x).intValue()%2 == 0);
            }
        };

        oddPred = new Predicate() {
            public boolean evaluate(Object x) { 
                return (((Integer)x).intValue()%2 == 1);
            }
        };

        threePred = new Predicate() {
            public boolean evaluate(Object x) { 
                return (((Integer)x).intValue()%3 == 0);
            }
        };

        fourPred = new Predicate() {
            public boolean evaluate(Object x) { 
                return (((Integer)x).intValue()%4 == 0);
            }
        };

    }

    public void tearDown() throws Exception {
        list = null;
        odds = null;
        evens = null;
        threes = null;
        fours = null;
        sixes = null;
        truePred = null;
        falsePred = null;
        evenPred = null;
        oddPred = null;
        threePred = null;
        fourPred = null;
    }

    public void testWalkLists() {
        // this just confirms that our walkLists method works OK
        walkLists(list,list.listIterator());
    }

    public void testManual() {
        // do this one "by hand" as a sanity check
        FilterListIterator filtered = new FilterListIterator(list.listIterator(),threePred);
        
        assertEquals(new Integer(0),filtered.next());
        assertEquals(new Integer(3),filtered.next());
        assertEquals(new Integer(6),filtered.next());
        assertEquals(new Integer(9),filtered.next());
        assertEquals(new Integer(12),filtered.next());
        assertEquals(new Integer(15),filtered.next());
        assertEquals(new Integer(18),filtered.next());

        assertEquals(new Integer(18),filtered.previous());
        assertEquals(new Integer(15),filtered.previous());
        assertEquals(new Integer(12),filtered.previous());
        assertEquals(new Integer(9),filtered.previous());
        assertEquals(new Integer(6),filtered.previous());
        assertEquals(new Integer(3),filtered.previous());
        assertEquals(new Integer(0),filtered.previous());
    
        assertTrue(!filtered.hasPrevious());

        assertEquals(new Integer(0),filtered.next());
        assertEquals(new Integer(3),filtered.next());
        assertEquals(new Integer(6),filtered.next());
        assertEquals(new Integer(9),filtered.next());
        assertEquals(new Integer(12),filtered.next());
        assertEquals(new Integer(15),filtered.next());
        assertEquals(new Integer(18),filtered.next());

        assertTrue(!filtered.hasNext());

        assertEquals(new Integer(18),filtered.previous());
        assertEquals(new Integer(15),filtered.previous());
        assertEquals(new Integer(12),filtered.previous());
        assertEquals(new Integer(9),filtered.previous());
        assertEquals(new Integer(6),filtered.previous());
        assertEquals(new Integer(3),filtered.previous());
        assertEquals(new Integer(0),filtered.previous());

        assertEquals(new Integer(0),filtered.next());
        assertEquals(new Integer(0),filtered.previous());
        assertEquals(new Integer(0),filtered.next());
        
        assertEquals(new Integer(3),filtered.next());
        assertEquals(new Integer(6),filtered.next());
        assertEquals(new Integer(6),filtered.previous());
        assertEquals(new Integer(3),filtered.previous());
        assertEquals(new Integer(3),filtered.next());
        assertEquals(new Integer(6),filtered.next());

        assertEquals(new Integer(9),filtered.next());
        assertEquals(new Integer(12),filtered.next());
        assertEquals(new Integer(15),filtered.next());
        assertEquals(new Integer(15),filtered.previous());
        assertEquals(new Integer(12),filtered.previous());
        assertEquals(new Integer(9),filtered.previous());

    }

    public void testTruePredicate() {
        FilterListIterator filtered = new FilterListIterator(list.listIterator(),truePred);
        walkLists(list,filtered);
    }
    
    public void testFalsePredicate() {
        FilterListIterator filtered = new FilterListIterator(list.listIterator(),falsePred);
        walkLists(new ArrayList(),filtered);
    }

    public void testEvens() {
        FilterListIterator filtered = new FilterListIterator(list.listIterator(),evenPred);
        walkLists(evens,filtered);
    }
    
    public void testOdds() {
        FilterListIterator filtered = new FilterListIterator(list.listIterator(),oddPred);
        walkLists(odds,filtered);
    }

    public void testThrees() {
        FilterListIterator filtered = new FilterListIterator(list.listIterator(),threePred);
        walkLists(threes,filtered);
    }

    public void testFours() {
        FilterListIterator filtered = new FilterListIterator(list.listIterator(),fourPred);
        walkLists(fours,filtered);
    }

    public void testNestedSixes() {
        FilterListIterator filtered = new FilterListIterator(
                                        new FilterListIterator(list.listIterator(),threePred),
                                        evenPred
                                      );
        walkLists(sixes,filtered);
    }

    public void testNestedSixes2() {
        FilterListIterator filtered = new FilterListIterator(
                                        new FilterListIterator(list.listIterator(),evenPred),
                                        threePred
                                      );
        walkLists(sixes,filtered);
    }

    public void testNestedSixes3() {        
        FilterListIterator filtered = new FilterListIterator(
                                        new FilterListIterator(list.listIterator(),threePred),
                                        evenPred
                                      );
        walkLists(sixes,new FilterListIterator(filtered,truePred));
    }

    public void testNextChangesPrevious() {
        {
            FilterListIterator filtered = new FilterListIterator(list.listIterator(),threePred);
            nextNextPrevious(threes.listIterator(),filtered);
        }
    
        {
            FilterListIterator filtered = new FilterListIterator(list.listIterator(),truePred);
            nextNextPrevious(list.listIterator(),filtered);
        }
    }

    public void testPreviousChangesNext() {
        {
            FilterListIterator filtered = new FilterListIterator(list.listIterator(),threePred);
            ListIterator expected = threes.listIterator();
            walkForward(expected,filtered);
            previousPreviousNext(expected,filtered);
        }
        {
            FilterListIterator filtered = new FilterListIterator(list.listIterator(),truePred);
            ListIterator expected = list.listIterator();
            walkForward(expected,filtered);
            previousPreviousNext(expected,filtered);
        }
    }

    public void testFailingHasNextBug() {
        FilterListIterator filtered = new FilterListIterator(list.listIterator(),fourPred);
        ListIterator expected = fours.listIterator();
        while(expected.hasNext()) {
            expected.next();
            filtered.next();
        }
        assertTrue(filtered.hasPrevious());
        assertTrue(!filtered.hasNext());
        assertEquals(expected.previous(),filtered.previous());
    }

    // Utilities

    private void walkForward(ListIterator expected, ListIterator testing) {
        while(expected.hasNext()) {
            assertEquals(expected.nextIndex(),testing.nextIndex());
            assertEquals(expected.previousIndex(),testing.previousIndex());
            assertTrue(testing.hasNext());
            assertEquals(expected.next(),testing.next());
        }
    }

    private void walkBackward(ListIterator expected, ListIterator testing) {
        while(expected.hasPrevious()) {
            assertEquals(expected.nextIndex(),testing.nextIndex());
            assertEquals(expected.previousIndex(),testing.previousIndex());
            assertTrue(testing.hasPrevious());
            assertEquals(expected.previous(),testing.previous());
        }
    }

    private void nextNextPrevious(ListIterator expected, ListIterator testing) {
        // calls to next() should change the value returned by previous()
        // even after previous() has been set by a call to hasPrevious()
        assertEquals(expected.next(),testing.next());
        assertEquals(expected.hasPrevious(),testing.hasPrevious());
        Object expecteda = expected.next();
        Object testinga = testing.next();
        assertEquals(expecteda,testinga);
        Object expectedb = expected.previous();
        Object testingb = testing.previous();
        assertEquals(expecteda,expectedb);
        assertEquals(testinga,testingb);
    }

    private void previousPreviousNext(ListIterator expected, ListIterator testing) {
        // calls to previous() should change the value returned by next()
        // even after next() has been set by a call to hasNext()
        assertEquals(expected.previous(),testing.previous());
        assertEquals(expected.hasNext(),testing.hasNext());
        Object expecteda = expected.previous();
        Object testinga = testing.previous();
        assertEquals(expecteda,testinga);
        Object expectedb = expected.next();
        Object testingb = testing.next();
        assertEquals(expecteda,testingb);
        assertEquals(expecteda,expectedb);
        assertEquals(testinga,testingb);
    }

    private void walkLists(List list, ListIterator testing) {
        ListIterator expected = list.listIterator();

        // walk all the way forward
        walkForward(expected,testing);

        // walk all the way back
        walkBackward(expected,testing);

        // forward,back,forward
        while(expected.hasNext()) {
            assertEquals(expected.nextIndex(),testing.nextIndex());
            assertEquals(expected.previousIndex(),testing.previousIndex());
            assertTrue(testing.hasNext());
            assertEquals(expected.next(),testing.next());
            assertTrue(testing.hasPrevious());
            assertEquals(expected.previous(),testing.previous());
            assertTrue(testing.hasNext());
            assertEquals(expected.next(),testing.next());
        }


        // walk all the way back
        walkBackward(expected,testing);

        for(int i=0;i<list.size();i++) {
            // walk forward i
            for(int j=0;j<i;j++) {
                assertEquals(expected.nextIndex(),testing.nextIndex());
                assertEquals(expected.previousIndex(),testing.previousIndex());
                assertTrue(expected.hasNext()); // if this one fails we've got a logic error in the test
                assertTrue(testing.hasNext());
                assertEquals(expected.next(),testing.next());
            }
            // walk back i/2
            for(int j=0;j<i/2;j++) {
                assertEquals(expected.nextIndex(),testing.nextIndex());
                assertEquals(expected.previousIndex(),testing.previousIndex());
                assertTrue(expected.hasPrevious()); // if this one fails we've got a logic error in the test
                assertTrue(testing.hasPrevious());
                assertEquals(expected.previous(),testing.previous());
            }
            // walk forward i/2
            for(int j=0;j<i/2;j++) {
                assertEquals(expected.nextIndex(),testing.nextIndex());
                assertEquals(expected.previousIndex(),testing.previousIndex());
                assertTrue(expected.hasNext()); // if this one fails we've got a logic error in the test
                assertTrue(testing.hasNext());
                assertEquals(expected.next(),testing.next());
            }
            // walk back i
            for(int j=0;j<i;j++) {
                assertEquals(expected.nextIndex(),testing.nextIndex());
                assertEquals(expected.previousIndex(),testing.previousIndex());
                assertTrue(expected.hasPrevious()); // if this one fails we've got a logic error in the test
                assertTrue(testing.hasPrevious());
                assertEquals(expected.previous(),testing.previous());
            }
        }

        // random walk
        StringBuffer walkdescr = new StringBuffer(500);
        for(int i=0;i<500;i++) {
            if(random.nextBoolean()) {
                // step forward
                walkdescr.append("+");
                if(expected.hasNext()) {
                    assertEquals(walkdescr.toString(),expected.next(),testing.next());
                }
            } else {
                // step backward
                walkdescr.append("-");
                if(expected.hasPrevious()) {
                    assertEquals(walkdescr.toString(),expected.previous(),testing.previous());
                }
            }
            assertEquals(walkdescr.toString(),expected.nextIndex(),testing.nextIndex());
            assertEquals(walkdescr.toString(),expected.previousIndex(),testing.previousIndex());
        }

    }

}

Other Commons Collections examples (source code examples)

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