Commons Collections example source code file (TestLoopingListIterator.java)

This example Commons Collections source code file (TestLoopingListIterator.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, exception, exception, list, list, loopinglistiterator, loopinglistiterator, nosuchelementexception, nullpointerexception, string, string, test, testcase, testloopinglistiterator, util

The Commons Collections TestLoopingListIterator.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.Arrays;
import java.util.List;
import java.util.NoSuchElementException;

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

/**
 * Tests the LoopingListIterator class.
 *
 * @version $Revision: 646780 $ $Date: 2008-04-10 13:48:07 +0100 (Thu, 10 Apr 2008) $
 *
 * @author Eric Crampton <ccesc@eonomine.com>
 */
public class TestLoopingListIterator extends TestCase {

    public TestLoopingListIterator(String testName) {
        super(testName);
    }
    
    public static Test suite() {
        return new TestSuite(TestLoopingListIterator.class);
    }

    /**
     * Tests constructor exception.
     */
    public void testConstructorEx() throws Exception {
        try {
            new LoopingListIterator(null);
            fail();
        } catch (NullPointerException ex) {
        }
    }

    /**
     * Tests whether an empty looping list iterator works.
     */
    public void testLooping0() throws Exception {
        List list = new ArrayList();
        LoopingListIterator loop = new LoopingListIterator(list);
        assertFalse(loop.hasNext());
        assertFalse(loop.hasPrevious());
        
        try {
            loop.next();
            fail();
        } catch (NoSuchElementException ex) {
        }

        try {
            loop.previous();
            fail();
        } catch (NoSuchElementException ex) {
        }
    }

    /**
     * Tests whether a looping list iterator works on a list with only
     * one element.
     */
    public void testLooping1() throws Exception {
        List list = new ArrayList(Arrays.asList(new String[] { "a" }));
        LoopingListIterator loop = new LoopingListIterator(list); // <a>

        assertTrue(loop.hasNext());
        assertEquals("a", loop.next());     // <a>

        assertTrue(loop.hasNext());
        assertEquals("a", loop.next());     // <a>

        assertTrue(loop.hasNext());
        assertEquals("a", loop.next());     // <a>

        assertTrue(loop.hasPrevious());
        assertEquals("a", loop.previous()); // <a>

        assertTrue(loop.hasPrevious());
        assertEquals("a", loop.previous()); // <a>

        assertTrue(loop.hasPrevious());
        assertEquals("a", loop.previous()); // <a>
    }

    /**
     * Tests whether a looping list iterator works on a list with two
     * elements.
     */
    public void testLooping2() throws Exception {
        List list = new ArrayList(Arrays.asList(new String[] { "a", "b" }));
        LoopingListIterator loop = new LoopingListIterator(list); // <a> b

        assertTrue(loop.hasNext());
        assertEquals("a", loop.next());     // a <b>

        assertTrue(loop.hasNext());
        assertEquals("b", loop.next());     // <a> b

        assertTrue(loop.hasNext());
        assertEquals("a", loop.next());     // a <b>

        // Reset the iterator and try using previous.
        loop.reset();                       // <a> b

        assertTrue(loop.hasPrevious());
        assertEquals("b", loop.previous()); // a <b>

        assertTrue(loop.hasPrevious());
        assertEquals("a", loop.previous()); // <a> b

        assertTrue(loop.hasPrevious());
        assertEquals("b", loop.previous()); // a <b>
    }

    /**
     * Tests jogging back and forth between two elements, but not over
     * the begin/end boundary of the list.
     */
    public void testJoggingNotOverBoundary() {
        List list = new ArrayList(Arrays.asList(new String[] { "a", "b" }));
        LoopingListIterator loop = new LoopingListIterator(list); // <a> b
    
        // Try jogging back and forth between the elements, but not
        // over the begin/end boundary.
        loop.reset();
        assertEquals("a", loop.next());     // a <b>
        assertEquals("a", loop.previous()); // <a> b
        assertEquals("a", loop.next());     // a <b>

        assertEquals("b", loop.next());     // <a> b
        assertEquals("b", loop.previous()); // a <b>
        assertEquals("b", loop.next());     // <a> b
    }

    /**
     * Tests jogging back and forth between two elements over the
     * begin/end boundary of the list.
     */
    public void testJoggingOverBoundary() {
        List list = new ArrayList(Arrays.asList(new String[] { "a", "b" }));
        LoopingListIterator loop = new LoopingListIterator(list); // <a> b
    
        // Try jogging back and forth between the elements, but not
        // over the begin/end boundary.
        assertEquals("b", loop.previous()); // a <b>
        assertEquals("b", loop.next());     // <a> b
        assertEquals("b", loop.previous()); // a <b>

        assertEquals("a", loop.previous()); // <a> b
        assertEquals("a", loop.next());     // a <b>
        assertEquals("a", loop.previous()); // <a> b
    }

    /**
     * Tests removing an element from a wrapped ArrayList.
     */
    public void testRemovingElementsAndIteratingForward() {
        List list = new ArrayList(Arrays.asList(new String[] { "a", "b", "c" }));
        LoopingListIterator loop = new LoopingListIterator(list); // <a> b c

        assertTrue(loop.hasNext());
        assertEquals("a", loop.next()); // a <b> c
        loop.remove();                  // <b> c
        assertEquals(2, list.size());

        assertTrue(loop.hasNext());
        assertEquals("b", loop.next()); // b <c>
        loop.remove();                  // <c>
        assertEquals(1, list.size());

        assertTrue(loop.hasNext());
        assertEquals("c", loop.next()); // <c>
        loop.remove();                  // ---
        assertEquals(0, list.size());

        assertFalse(loop.hasNext());
        try {
            loop.next();
            fail();
        } catch (NoSuchElementException ex) {
        }
    }

    /**
     * Tests removing an element from a wrapped ArrayList.
     */
    public void testRemovingElementsAndIteratingBackwards() {
        List list = new ArrayList(Arrays.asList(new String[] { "a", "b", "c" }));
        LoopingListIterator loop = new LoopingListIterator(list); // <a> b c

        assertTrue(loop.hasPrevious());
        assertEquals("c", loop.previous()); // a b <c>
        loop.remove();                      // <a> b
        assertEquals(2, list.size());

        assertTrue(loop.hasPrevious());
        assertEquals("b", loop.previous()); // a <b>
        loop.remove();                      // <a>
        assertEquals(1, list.size());

        assertTrue(loop.hasPrevious());
        assertEquals("a", loop.previous()); // <a>
        loop.remove();                      // ---
        assertEquals(0, list.size());

        assertFalse(loop.hasPrevious());
        try {
            loop.previous();
            fail();
        } catch (NoSuchElementException ex) {
        }
    }

    /**
     * Tests the reset method.
     */
    public void testReset() {
        List list = new ArrayList(Arrays.asList(new String[] { "a", "b", "c" }));
        LoopingListIterator loop = new LoopingListIterator(list); // <a> b c

        assertEquals("a", loop.next()); // a <b> c
        assertEquals("b", loop.next()); // a b <c>
        loop.reset();                   // <a> b c
        assertEquals("a", loop.next()); // a <b> c
        loop.reset();                   // <a> b c
        assertEquals("a", loop.next()); // a <b> c
        assertEquals("b", loop.next()); // a b <c>
        assertEquals("c", loop.next()); // <a> b c
        loop.reset();                   // <a> b c

        assertEquals("c", loop.previous()); // a b <c>
        assertEquals("b", loop.previous()); // a <b> c
        loop.reset();                       // <a> b c
        assertEquals("c", loop.previous()); // a b <c>
        loop.reset();                       // <a> b c
        assertEquals("c", loop.previous()); // a b <c>
        assertEquals("b", loop.previous()); // a <b> c
        assertEquals("a", loop.previous()); // <a> b c
    }

    /**
     * Tests the add method.
     */
    public void testAdd() {
        List list = new ArrayList(Arrays.asList(new String[] { "b", "e", "f" }));
        LoopingListIterator loop = new LoopingListIterator(list); // <b> e f

        loop.add("a");                      // <a> b e f
        assertEquals("b", loop.next());     // a <b> e f
        loop.reset();                       // <a> b e f
        assertEquals("a", loop.next());     // a <b> e f
        assertEquals("b", loop.next());     // a b <e> f

        loop.add("c");                      // a b c <e> f
        assertEquals("e", loop.next());     // a b c e <f>
        assertEquals("e", loop.previous()); // a b c <e> f
        assertEquals("c", loop.previous()); // a b <c> e f
        assertEquals("c", loop.next());     // a b c <e> f
        
        loop.add("d");                      // a b c d <e> f
        loop.reset();                       // <a> b c d e f
        assertEquals("a", loop.next());     // a <b> c d e f
        assertEquals("b", loop.next());     // a b <c> d e f
        assertEquals("c", loop.next());     // a b c <d> e f
        assertEquals("d", loop.next());     // a b c d <e> f
        assertEquals("e", loop.next());     // a b c d e <f>
        assertEquals("f", loop.next());     // <a> b c d e f
        assertEquals("a", loop.next());     // a <b> c d e f

        list = new ArrayList(Arrays.asList(new String[] { "b", "e", "f" }));
        loop = new LoopingListIterator(list); // <b> e f        

        loop.add("a");                      // a <b> e f
        assertEquals("a", loop.previous()); // a b e <f>
        loop.reset();                       // <a> b e f
        assertEquals("f", loop.previous()); // a b e <f>
        assertEquals("e", loop.previous()); // a b <e> f

        loop.add("d");                      // a b d <e> f
        assertEquals("d", loop.previous()); // a b <d> e f

        loop.add("c");                      // a b c <d> e f
        assertEquals("c", loop.previous()); // a b <c> d e f

        loop.reset();
        assertEquals("a", loop.next());     // a <b> c d e f
        assertEquals("b", loop.next());     // a b <c> d e f
        assertEquals("c", loop.next());     // a b c <d> e f
        assertEquals("d", loop.next());     // a b c d <e> f
        assertEquals("e", loop.next());     // a b c d e <f>
        assertEquals("f", loop.next());     // <a> b c d e f
        assertEquals("a", loop.next());     // a <b> c d e f
    }

    /**
     * Tests nextIndex and previousIndex.
     */
    public void testNextAndPreviousIndex() {
        List list = new ArrayList(Arrays.asList(new String[] { "a", "b", "c" }));
        LoopingListIterator loop = new LoopingListIterator(list); // <a> b c

        assertEquals(0, loop.nextIndex());
        assertEquals(2, loop.previousIndex());

        assertEquals("a", loop.next());        // a <b> c
        assertEquals(1, loop.nextIndex());
        assertEquals(0, loop.previousIndex());

        assertEquals("a", loop.previous());    // <a> b c
        assertEquals(0, loop.nextIndex());
        assertEquals(2, loop.previousIndex());

        assertEquals("c", loop.previous());    // a b <c>
        assertEquals(2, loop.nextIndex());
        assertEquals(1, loop.previousIndex());

        assertEquals("b", loop.previous());    // a <b> c
        assertEquals(1, loop.nextIndex());
        assertEquals(0, loop.previousIndex());

        assertEquals("a", loop.previous());    // <a> b c
        assertEquals(0, loop.nextIndex());
        assertEquals(2, loop.previousIndex());
    }

    /**
     * Tests using the set method to change elements.
     */
    public void testSet() {
        List list = new ArrayList(Arrays.asList(new String[] { "q", "r", "z" }));
        LoopingListIterator loop = new LoopingListIterator(list); // <q> r z

        assertEquals("z", loop.previous()); // q r <z>
        loop.set("c");                      // q r <c>

        loop.reset();                       // <q> r c
        assertEquals("q", loop.next());     // q <r> c
        loop.set("a");                      // a <r> c
        
        assertEquals("r", loop.next());     // a r <c>
        loop.set("b");                      // a b <c>

        loop.reset();                       // <a> b c
        assertEquals("a", loop.next());     // a <b> c
        assertEquals("b", loop.next());     // a b <c>
        assertEquals("c", loop.next());     // <a> b c
    }
    
}