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     */
017    package org.apache.commons.collections;
018    
019    import java.util.Iterator;
020    
021    /**
022     * Defines an iterator that operates over an ordered collection.
023     * <p>
024     * This iterator allows both forward and reverse iteration through the collection.
025     *  
026     * @since Commons Collections 3.0
027     * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
028     *
029     * @author Stephen Colebourne
030     */
031    public interface OrderedIterator extends Iterator {
032    
033        /**
034         * Checks to see if there is a previous element that can be iterated to.
035         *
036         * @return <code>true</code> if the iterator has a previous element
037         */
038        boolean hasPrevious();
039    
040        /**
041         * Gets the previous element from the collection.
042         *
043         * @return the previous element in the iteration
044         * @throws java.util.NoSuchElementException if the iteration is finished
045         */
046        Object previous();
047    
048    }