/*
 *  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 java.util;


/**
 * An ListIterator is used to sequence over a List of objects. ListIterator can
 * move backwards or forwards through the List.
 */
public interface ListIterator<E> extends Iterator<E> {
	
	/**
	 * Inserts the specified object into the list between <code>next</code>
	 * and <code>previous</code>. The object inserted will be the previous
	 * object.
	 * 
	 * @param object
	 *            the object to insert
	 * 
	 * @exception UnsupportedOperationException
	 *                when adding is not supported by the list being iterated
	 * @exception ClassCastException
	 *                when the class of the object is inappropriate for the list
	 * @exception IllegalArgumentException
	 *                when the object cannot be added to the list
	 */
	void add(E object);

	/**
	 * Answers if there are more elements to iterate.
	 * 
	 * @return true if there are more elements, false otherwise
	 * 
	 * @see #next
	 */
	public boolean hasNext();

	/**
	 * Answers if there are previous elements to iterate.
	 * 
	 * @return true if there are previous elements, false otherwise
	 * 
	 * @see #previous
	 */
	public boolean hasPrevious();

	/**
	 * Answers the next object in the iteration.
	 * 
	 * @return the next object
	 * 
	 * @exception NoSuchElementException
	 *                when there are no more elements
	 * 
	 * @see #hasNext
	 */
	public E next();

	/**
	 * Answers the index of the next object in the iteration.
	 * 
	 * @return the index of the next object
	 * 
	 * @exception NoSuchElementException
	 *                when there are no more elements
	 * 
	 * @see #next
	 */
	public int nextIndex();

	/**
	 * Answers the previous object in the iteration.
	 * 
	 * @return the previous object
	 * 
	 * @exception NoSuchElementException
	 *                when there are no previous elements
	 * 
	 * @see #hasPrevious
	 */
	public E previous();

	/**
	 * Answers the index of the previous object in the iteration.
	 * 
	 * @return the index of the previous object
	 * 
	 * @exception NoSuchElementException
	 *                when there are no previous elements
	 * 
	 * @see #previous
	 */
	public int previousIndex();

	/**
	 * Removes the last object returned by <code>next</code> or
	 * <code>previous</code> from the list.
	 * 
	 * @exception UnsupportedOperationException
	 *                when removing is not supported by the list being iterated
	 * @exception IllegalStateException
	 *                when <code>next</code> or <code>previous</code> have
	 *                not been called, or <code>remove</code> or
	 *                <code>add</code> have already been called after the last
	 *                call to <code>next</code> or <code>previous</code>
	 */
	public void remove();

	/**
	 * Replaces the last object returned by <code>next</code> or
	 * <code>previous</code> with the specified object.
	 * 
	 * @param object
	 *            the object to add
	 * 
	 * @exception UnsupportedOperationException
	 *                when adding is not supported by the list being iterated
	 * @exception ClassCastException
	 *                when the class of the object is inappropriate for the list
	 * @exception IllegalArgumentException
	 *                when the object cannot be added to the list
	 * @exception IllegalStateException
	 *                when <code>next</code> or <code>previous</code> have
	 *                not been called, or <code>remove</code> or
	 *                <code>add</code> have already been called after the last
	 *                call to <code>next</code> or <code>previous</code>
	 */
	void set(E object);
}
