| /* |
| * 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.util.ListIterator; |
| import java.util.NoSuchElementException; |
| |
| import org.apache.commons.collections.ResettableListIterator; |
| |
| /** |
| * Implements a {@link ListIterator} over an array of objects. |
| * <p> |
| * This iterator does not support {@link #add} or {@link #remove}, as the object array |
| * cannot be structurally modified. The {@link #set} method is supported however. |
| * <p> |
| * The iterator implements a {@link #reset} method, allowing the reset of the iterator |
| * back to the start if required. |
| * |
| * @see org.apache.commons.collections.iterators.ObjectArrayIterator |
| * @see java.util.Iterator |
| * @see java.util.ListIterator |
| * |
| * @since Commons Collections 3.0 |
| * @version $Revision: 1.1 $ $Date: 2009/05/27 22:16:27 $ |
| * |
| * @author Neil O'Toole |
| * @author Stephen Colebourne |
| * @author Phil Steitz |
| */ |
| public class ObjectArrayListIterator extends ObjectArrayIterator |
| 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; |
| |
| /** |
| * Constructor for use with <code>setArray</code>. |
| * <p> |
| * Using this constructor, the iterator is equivalent to an empty iterator |
| * until {@link #setArray} is called to establish the array to iterate over. |
| */ |
| public ObjectArrayListIterator() { |
| super(); |
| } |
| |
| /** |
| * Constructs an ObjectArrayListIterator that will iterate over the values in the |
| * specified array. |
| * |
| * @param array the array to iterate over |
| * @throws NullPointerException if <code>array</code> is <code>null</code> |
| */ |
| public ObjectArrayListIterator(Object[] array) { |
| super(array); |
| } |
| |
| /** |
| * Constructs an ObjectArrayListIterator that will iterate over the values in the |
| * specified array from a specific start index. |
| * |
| * @param array the array to iterate over |
| * @param start the index to start iterating at |
| * @throws NullPointerException if <code>array</code> is <code>null</code> |
| * @throws IndexOutOfBoundsException if the start index is out of bounds |
| */ |
| public ObjectArrayListIterator(Object[] array, int start) { |
| super(array, start); |
| } |
| |
| /** |
| * Construct an ObjectArrayListIterator that will iterate over a range of values |
| * in the specified array. |
| * |
| * @param array the array to iterate over |
| * @param start the index to start iterating at |
| * @param end the index (exclusive) to finish iterating at |
| * @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 ObjectArrayListIterator(Object[] array, int start, int end) { |
| super(array, start, end); |
| } |
| |
| // 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 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 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 array's size, and so will |
| * always throw an {@link UnsupportedOperationException} when this method is invoked. |
| * |
| * @param obj the object to add |
| * @throws UnsupportedOperationException always thrown. |
| */ |
| public void add(Object obj) { |
| 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()}. |
| * |
| * <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. |
| * |
| * @param obj the object to set into the array |
| * @throws IllegalStateException if next() has not yet been called. |
| * @throws ClassCastException if the object type is unsuitable for the array |
| */ |
| public void set(Object obj) { |
| if (this.lastItemIndex == -1) { |
| throw new IllegalStateException("must call next() or previous() before a call to set()"); |
| } |
| |
| this.array[this.lastItemIndex] = obj; |
| } |
| |
| /** |
| * Resets the iterator back to the start index. |
| */ |
| public void reset() { |
| super.reset(); |
| this.lastItemIndex = -1; |
| } |
| |
| } |