- /*
- * Copyright 1999-2004 The Apache Software Foundation
- *
- * Licensed 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.lang.reflect.Array;
- import java.util.ListIterator;
- import java.util.NoSuchElementException;
-
- import org.apache.commons.collections.ResettableListIterator;
-
- /**
- * Implements a {@link ListIterator} over an array.
- * <p>
- * 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.
- *
- * <p>
- * 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: 1.12 $ $Date: 2004/02/18 00:59:50 $
- *
- * @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 <code>next()</code>
- * or <code>previous()</code>. This is set to <code>-1</code> if neither method
- * has yet been invoked. <code>lastItemIndex</code> is used to to implement
- * the {@link #set} method.
- *
- */
- protected int lastItemIndex = -1;
-
- // Constructors
- // ----------------------------------------------------------------------
- /**
- * Constructor for use with <code>setArray</code>.
- * <p>
- * 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 <code>array</code> is not an array.
- * @throws NullPointerException if <code>array</code> is <code>null</code>
- */
- 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 <code>array</code> is not an array.
- * @throws NullPointerException if <code>array</code> is <code>null</code>
- * @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 <code>array</code> 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 <code>array</code> is <code>null</code>
- */
- 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.
- * <p>
- * This method sets the element that was returned by the last call
- * to {@link #next()} of {@link #previous()}.
- * <p>
- * <b>Note:</b> {@link ListIterator} implementations that support
- * <code>add()</code> and <code>remove()</code> only allow <code>set()</code> to be called
- * once per call to <code>next()</code> or <code>previous</code> (see the {@link ListIterator}
- * javadoc for more details). Since this implementation does
- * not support <code>add()</code> or <code>remove()</code>, <code>set()</code> 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;
- }
-
- }