001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.wicket.util.collections;
018
019import java.util.Iterator;
020import java.util.List;
021import java.util.ListIterator;
022
023/**
024 * An iterator over {@link List} which goes from the end to the start
025 * 
026 * @param <E>
027 */
028public class ReverseListIterator<E> implements Iterator<E>, Iterable<E>
029{
030        private final ListIterator<E> delegateIterator;
031
032        /**
033         * Construct.
034         * 
035         * @param list
036         *            the list which will be iterated in reverse order
037         */
038        public ReverseListIterator(final List<E> list)
039        {
040                int start = list.size();
041                this.delegateIterator = list.listIterator(start);
042        }
043
044        @Override
045        public boolean hasNext()
046        {
047                return delegateIterator.hasPrevious();
048        }
049
050        @Override
051        public E next()
052        {
053                return delegateIterator.previous();
054        }
055
056        @Override
057        public void remove()
058        {
059                throw new UnsupportedOperationException();
060        }
061
062        @Override
063        public Iterator<E> iterator()
064        {
065                return this;
066        }
067
068}