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.commons.collections4;
018
019import java.util.Iterator;
020
021/**
022 * Defines an iterator that operates over an ordered container. Subset of {@link java.util.ListIterator}.
023 * <p>
024 * This iterator allows both forward and reverse iteration through the container.
025 *
026 * @param <E> the type to iterate over
027 * @since 3.0
028 */
029public interface OrderedIterator<E> extends Iterator<E> {
030
031    /**
032     * Checks to see if there is a previous element that can be iterated to.
033     *
034     * @return <code>true</code> if the iterator has a previous element
035     */
036    boolean hasPrevious();
037
038    /**
039     * Gets the previous element from the container.
040     *
041     * @return the previous element in the iteration
042     * @throws java.util.NoSuchElementException if the iteration is finished
043     */
044    E previous();
045
046}