| /* |
| * 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.collections4.iterators; |
| |
| import java.lang.reflect.Array; |
| import java.util.NoSuchElementException; |
| |
| import org.apache.commons.collections4.ResettableListIterator; |
| |
| /** |
| * Implements a {@link java.util.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. |
| * |
| * @param <E> the type of elements returned by this iterator. |
| * @see org.apache.commons.collections4.iterators.ArrayIterator |
| * @see java.util.Iterator |
| * @see java.util.ListIterator |
| * |
| * @since 3.0 |
| */ |
| public class ArrayListIterator<E> extends ArrayIterator<E> |
| implements ResettableListIterator<E> { |
| |
| /** |
| * Holds the index of the last item returned by a call to {@code next()} |
| * or {@code previous()}. This is set to {@code -1} if neither method |
| * has yet been invoked. {@code lastItemIndex} is used to to implement |
| * the {@link #set} method. |
| */ |
| private int lastItemIndex = -1; |
| |
| // Constructors |
| // ---------------------------------------------------------------------- |
| /** |
| * 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} is not an array. |
| * @throws NullPointerException if {@code array} is {@code null} |
| */ |
| public ArrayListIterator(final 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} is not an array. |
| * @throws NullPointerException if {@code array} is {@code null} |
| * @throws IndexOutOfBoundsException if the start index is out of bounds |
| */ |
| public ArrayListIterator(final Object array, final int startIndex) { |
| super(array, 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} 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} is {@code null} |
| */ |
| public ArrayListIterator(final Object array, final int startIndex, final int endIndex) { |
| super(array, startIndex, endIndex); |
| } |
| |
| // ListIterator interface |
| //----------------------------------------------------------------------- |
| /** |
| * Returns true if there are previous elements to return from the array. |
| * |
| * @return true if there is a previous element to return |
| */ |
| @Override |
| 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 |
| */ |
| @Override |
| @SuppressWarnings("unchecked") |
| public E previous() { |
| if (hasPrevious() == false) { |
| throw new NoSuchElementException(); |
| } |
| this.lastItemIndex = --this.index; |
| return (E) 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 |
| */ |
| @Override |
| @SuppressWarnings("unchecked") |
| public E next() { |
| if (hasNext() == false) { |
| throw new NoSuchElementException(); |
| } |
| this.lastItemIndex = this.index; |
| return (E) Array.get(this.array, this.index++); |
| } |
| |
| /** |
| * Gets the next index to be retrieved. |
| * |
| * @return the index of the item to be retrieved next |
| */ |
| @Override |
| 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 |
| */ |
| @Override |
| 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. |
| * |
| * @param o the element to add |
| * @throws UnsupportedOperationException always thrown. |
| * @see java.util.ListIterator#set |
| */ |
| @Override |
| public void add(final 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 java.util.ListIterator} implementations that support |
| * {@code add()} and {@code remove()} only allow {@code set()} to be called |
| * once per call to {@code next()} or {@code previous} (see the {@link java.util.ListIterator} |
| * javadoc for more details). Since this implementation does |
| * not support {@code add()} or {@code remove()}, {@code set()} may be |
| * called as often as desired. |
| * |
| * @param o the element to set |
| * @throws IllegalStateException if {@link #next()} or {@link #previous()} has not been called |
| * before {@link #set(Object)} |
| * @see java.util.ListIterator#set |
| */ |
| @Override |
| public void set(final 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. |
| */ |
| @Override |
| public void reset() { |
| super.reset(); |
| this.lastItemIndex = -1; |
| } |
| |
| } |