| /* |
| * 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.util.NoSuchElementException; |
| |
| import org.apache.commons.collections4.ResettableListIterator; |
| |
| /** |
| * Implements a {@link java.util.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. |
| * |
| * @param <E> the type of elements returned by this iterator. |
| * @see org.apache.commons.collections4.iterators.ObjectArrayIterator |
| * @see java.util.Iterator |
| * @see java.util.ListIterator |
| * |
| * @since 3.0 |
| */ |
| public class ObjectArrayListIterator<E> extends ObjectArrayIterator<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; |
| |
| //------------------------------------------------------------------------- |
| /** |
| * 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} is {@code null} |
| */ |
| public ObjectArrayListIterator(final E... 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} is {@code null} |
| * @throws IndexOutOfBoundsException if the start index is out of bounds |
| */ |
| public ObjectArrayListIterator(final E[] array, final 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} is {@code null} |
| */ |
| public ObjectArrayListIterator(final E[] array, final int start, final 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 |
| */ |
| @Override |
| public boolean hasPrevious() { |
| return this.index > getStartIndex(); |
| } |
| |
| /** |
| * Gets the previous element from the array. |
| * |
| * @return the previous element |
| * @throws NoSuchElementException if there is no previous element |
| */ |
| @Override |
| public E 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 |
| */ |
| @Override |
| public E 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 |
| */ |
| @Override |
| public int nextIndex() { |
| return this.index - getStartIndex(); |
| } |
| |
| /** |
| * 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 - getStartIndex() - 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. |
| */ |
| @Override |
| public void add(final E 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 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 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 |
| */ |
| @Override |
| public void set(final E 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. |
| */ |
| @Override |
| public void reset() { |
| super.reset(); |
| this.lastItemIndex = -1; |
| } |
| |
| } |