1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.collections4;
18
19 import java.util.Iterator;
20
21 /**
22 * Defines an iterator that operates over an ordered container. Subset of {@link java.util.ListIterator}.
23 * <p>
24 * This iterator allows both forward and reverse iteration through the container.
25 * </p>
26 *
27 * @param <E> the type of elements returned by this iterator.
28 * @since 3.0
29 */
30 public interface OrderedIterator<E> extends Iterator<E> {
31
32 /**
33 * Checks to see if there is a previous element that can be iterated to.
34 *
35 * @return {@code true} if the iterator has a previous element
36 */
37 boolean hasPrevious();
38
39 /**
40 * Gets the previous element from the container.
41 *
42 * @return the previous element in the iteration
43 * @throws java.util.NoSuchElementException if the iteration is finished
44 */
45 E previous();
46
47 }