01: /*
02: * Copyright 2002-2004 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.Comparator;
19:
20: /**
21: * Defines a type of <code>Bag</code> that maintains a sorted order among
22: * its unique representative members.
23: *
24: * @since Commons Collections 2.0
25: * @version $Revision: 155406 $ $Date: 2005-02-26 12:55:26 +0000 (Sat, 26 Feb 2005) $
26: *
27: * @author Chuck Burdick
28: */
29: public interface SortedBag extends Bag {
30:
31: /**
32: * Returns the comparator associated with this sorted set, or null
33: * if it uses its elements' natural ordering.
34: *
35: * @return the comparator in use, or null if natural ordering
36: */
37: public Comparator comparator();
38:
39: /**
40: * Returns the first (lowest) member.
41: *
42: * @return the first element in the sorted bag
43: */
44: public Object first();
45:
46: /**
47: * Returns the last (highest) member.
48: *
49: * @return the last element in the sorted bag
50: */
51: public Object last();
52:
53: }
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