01: /*
02: * Copyright 2003-2004 The Apache Software Foundation
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
10: * Unless required by applicable law or agreed to in writing, software
11: * distributed under the License is distributed on an "AS IS" BASIS,
12: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13: * See the License for the specific language governing permissions and
14: * limitations under the License.
15: */
16: package org.apache.commons.collections;
17:
18: import java.util.Iterator;
19:
20: /**
21: * Defines an iterator that operates over an ordered collection.
22: * <p>
23: * This iterator allows both forward and reverse iteration through the collection.
24: *
25: * @since Commons Collections 3.0
26: * @version $Revision: 155406 $ $Date: 2005-02-26 12:55:26 +0000 (Sat, 26 Feb 2005) $
27: *
28: * @author Stephen Colebourne
29: */
30: public interface OrderedIterator extends Iterator {
31:
32: /**
33: * Checks to see if there is a previous element that can be iterated to.
34: *
35: * @return <code>true</code> if the iterator has a previous element
36: */
37: boolean hasPrevious();
38:
39: /**
40: * Gets the previous element from the collection.
41: *
42: * @return the previous element in the iteration
43: * @throws java.util.NoSuchElementException if the iteration is finished
44: */
45: Object previous();
46:
47: }
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