All Downloads are FREE. Search and download functionalities are using the official Maven repository.

org.apache.commons.collections.iterators.ArrayListIterator Maven / Gradle / Ivy

There is a newer version: 20040616
Show newest version
/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999-2004 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact [email protected].
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * .
 */
package org.apache.commons.collections.iterators;

import java.lang.reflect.Array;
import java.util.ListIterator;
import java.util.NoSuchElementException;

import org.apache.commons.collections.ResettableListIterator;

/**
 * Implements a {@link ListIterator} over an array. 
 * 

* The array can be either an array of object or of primitives. If you know * that you have an object array, the {@link ObjectArrayListIterator} * class is a better choice, as it will perform better. * *

* This iterator does not support {@link #add(Object)} or {@link #remove()}, as the array * cannot be changed in size. The {@link #set(Object)} method is supported however. * * @see org.apache.commons.collections.iterators.ArrayIterator * @see java.util.Iterator * @see java.util.ListIterator * * @since Commons Collections 3.0 * @version $Revision: 1.11 $ $Date: 2004/01/14 21:43:14 $ * * @author Neil O'Toole * @author Stephen Colebourne * @author Phil Steitz */ public class ArrayListIterator extends ArrayIterator implements ListIterator, ResettableListIterator { /** * Holds the index of the last item returned by a call to next() * or previous(). This is set to -1 if neither method * has yet been invoked. lastItemIndex is used to to implement * the {@link #set} method. * */ protected int lastItemIndex = -1; // Constructors // ---------------------------------------------------------------------- /** * Constructor for use with setArray. *

* Using this constructor, the iterator is equivalent to an empty iterator * until {@link #setArray(Object)} is called to establish the array to iterate over. */ public ArrayListIterator() { super(); } /** * Constructs an ArrayListIterator that will iterate over the values in the * specified array. * * @param array the array to iterate over * @throws IllegalArgumentException if array is not an array. * @throws NullPointerException if array is null */ public ArrayListIterator(Object array) { super(array); } /** * Constructs an ArrayListIterator that will iterate over the values in the * specified array from a specific start index. * * @param array the array to iterate over * @param startIndex the index to start iterating at * @throws IllegalArgumentException if array is not an array. * @throws NullPointerException if array is null * @throws IndexOutOfBoundsException if the start index is out of bounds */ public ArrayListIterator(Object array, int startIndex) { super(array, startIndex); this.startIndex = startIndex; } /** * Construct an ArrayListIterator that will iterate over a range of values * in the specified array. * * @param array the array to iterate over * @param startIndex the index to start iterating at * @param endIndex the index (exclusive) to finish iterating at * @throws IllegalArgumentException if array is not an array. * @throws IndexOutOfBoundsException if the start or end index is out of bounds * @throws IllegalArgumentException if end index is before the start * @throws NullPointerException if array is null */ public ArrayListIterator(Object array, int startIndex, int endIndex) { super(array, startIndex, endIndex); this.startIndex = startIndex; } // ListIterator interface //----------------------------------------------------------------------- /** * Returns true if there are previous elements to return from the array. * * @return true if there is a previous element to return */ public boolean hasPrevious() { return (this.index > this.startIndex); } /** * Gets the previous element from the array. * * @return the previous element * @throws NoSuchElementException if there is no previous element */ public Object previous() { if (hasPrevious() == false) { throw new NoSuchElementException(); } this.lastItemIndex = --this.index; return Array.get(this.array, this.index); } /** * Gets the next element from the array. * * @return the next element * @throws NoSuchElementException if there is no next element */ public Object next() { if (hasNext() == false) { throw new NoSuchElementException(); } this.lastItemIndex = this.index; return Array.get(this.array, this.index++); } /** * Gets the next index to be retrieved. * * @return the index of the item to be retrieved next */ public int nextIndex() { return this.index - this.startIndex; } /** * Gets the index of the item to be retrieved if {@link #previous()} is called. * * @return the index of the item to be retrieved next */ public int previousIndex() { return this.index - this.startIndex - 1; } /** * This iterator does not support modification of its backing collection, and so will * always throw an {@link UnsupportedOperationException} when this method is invoked. * * @throws UnsupportedOperationException always thrown. * @see java.util.ListIterator#set */ public void add(Object o) { throw new UnsupportedOperationException("add() method is not supported"); } /** * Sets the element under the cursor. *

* This method sets the element that was returned by the last call * to {@link #next()} of {@link #previous()}. *

* Note: {@link ListIterator} implementations that support * add() and remove() only allow set() to be called * once per call to next() or previous (see the {@link ListIterator} * javadoc for more details). Since this implementation does * not support add() or remove(), set() may be * called as often as desired. * * @see java.util.ListIterator#set */ public void set(Object o) { if (this.lastItemIndex == -1) { throw new IllegalStateException("must call next() or previous() before a call to set()"); } Array.set(this.array, this.lastItemIndex, o); } /** * Resets the iterator back to the start index. */ public void reset() { super.reset(); this.lastItemIndex = -1; } }





© 2015 - 2024 Weber Informatics LLC | Privacy Policy