Commons Collections example source code file (TestIteratorChain.java)

This example Commons Collections source code file (TestIteratorChain.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, four, integer, integer, iterator, iterator, iteratorchain, list, list, object, six, testiteratorchain, two, util

The Commons Collections TestIteratorChain.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.Iterator;
import java.util.List;
import java.util.NoSuchElementException;

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

import org.apache.commons.collections.IteratorUtils;
import org.apache.commons.collections.Predicate;

/**
 * Tests the IteratorChain class.
 * 
 * @version $Revision: 646780 $ $Date: 2008-04-10 13:48:07 +0100 (Thu, 10 Apr 2008) $
 * 
 * @author James Strachan
 * @author Mauricio S. Moura
 * @author Morgan Delagrange
 */
public class TestIteratorChain extends AbstractTestIterator {

    protected String[] testArray = {
        "One", "Two", "Three", "Four", "Five", "Six"
    };

    protected List list1 = null;
    protected List list2 = null;
    protected List list3 = null;

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

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

    public void setUp() {
        list1 = new ArrayList();
        list1.add("One");
        list1.add("Two");
        list1.add("Three");
        list2 = new ArrayList();
        list2.add("Four");
        list3 = new ArrayList();
        list3.add("Five");
        list3.add("Six");        
    }

    public Iterator makeEmptyIterator() {
        ArrayList list = new ArrayList();
        return new IteratorChain(list.iterator());
    }

    public Iterator makeFullIterator() {
        IteratorChain chain = new IteratorChain();

        chain.addIterator(list1.iterator());
        chain.addIterator(list2.iterator());
        chain.addIterator(list3.iterator());
        return chain;
    }

    public void testIterator() {
        Iterator iter = (Iterator) makeFullIterator();
        for ( int i = 0; i < testArray.length; i++ ) {
            Object testValue = testArray[i];            
            Object iterValue = iter.next();

            assertEquals( "Iteration value is correct", testValue, iterValue );
        }

        assertTrue("Iterator should now be empty", ! iter.hasNext() );

        try {
            Object testValue = iter.next();
        } catch (Exception e) {
            assertTrue("NoSuchElementException must be thrown", 
                       e.getClass().equals((new NoSuchElementException()).getClass()));
        }
    }

    public void testRemoveFromFilteredIterator() {

        final Predicate myPredicate = new Predicate() {
            public boolean evaluate( Object object ) {
                Integer i = (Integer) object;
                if (i.compareTo(new Integer(4)) < 0)
                    return true;
                return false;
            }
        };

        List list1 = new ArrayList();
        List list2 = new ArrayList();

        list1.add(new Integer(1));
        list1.add(new Integer(2));
        list2.add(new Integer(3));
        list2.add(new Integer(4)); // will be ignored by the predicate

        Iterator it1 = IteratorUtils.filteredIterator(list1.iterator(), myPredicate );
        Iterator it2 = IteratorUtils.filteredIterator(list2.iterator(), myPredicate );

        Iterator it = IteratorUtils.chainedIterator(it1, it2);
        while (it.hasNext()) {
            it.next();
            it.remove();
        }
        assertEquals( 0, list1.size() );
        assertEquals( 1, list2.size() );

    }
    
    public void testRemove() {
        Iterator iter = (Iterator) makeFullIterator();

        try {
            iter.remove();
            fail("Calling remove before the first call to next() should throw an exception");
        } catch (IllegalStateException e) {

        }

        for ( int i = 0; i < testArray.length; i++ ) {
            Object testValue = testArray[i];            
            Object iterValue = iter.next();

            assertEquals( "Iteration value is correct", testValue, iterValue );

            if (! iterValue.equals("Four")) {
                iter.remove();
            }
        }

        assertTrue("List is empty",list1.size() == 0);
        assertTrue("List is empty",list2.size() == 1);
        assertTrue("List is empty",list3.size() == 0);
    }

    public void testFirstIteratorIsEmptyBug() {
        List empty = new ArrayList();
        List notEmpty = new ArrayList();
        notEmpty.add("A");
        notEmpty.add("B");
        notEmpty.add("C");
        IteratorChain chain = new IteratorChain();
        chain.addIterator(empty.iterator());
        chain.addIterator(notEmpty.iterator());
        assertTrue("should have next",chain.hasNext());
        assertEquals("A",chain.next());
        assertTrue("should have next",chain.hasNext());
        assertEquals("B",chain.next());
        assertTrue("should have next",chain.hasNext());
        assertEquals("C",chain.next());
        assertTrue("should not have next",!chain.hasNext());
    }
    
    public void testEmptyChain() {
        IteratorChain chain = new IteratorChain();
        assertEquals(false, chain.hasNext());
        try {
            chain.next();
            fail();
        } catch (NoSuchElementException ex) {}
        try {
            chain.remove();
            fail();
        } catch (IllegalStateException ex) {}
    }
        
}