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.collections;
18
19 /**
20 * Defines a map that allows bidirectional lookup between key and values
21 * and retains and provides access to an ordering.
22 * <p>
23 * Implementations should allow a value to be looked up from a key and
24 * a key to be looked up from a value with equal performance.
25 *
26 * @since Commons Collections 3.0
27 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
28 *
29 * @author Stephen Colebourne
30 */
31 public interface OrderedBidiMap extends BidiMap, OrderedMap {
32
33 /**
34 * Gets a view of this map where the keys and values are reversed.
35 * <p>
36 * Changes to one map will be visible in the other and vice versa.
37 * This enables both directions of the map to be accessed equally.
38 * <p>
39 * Implementations should seek to avoid creating a new object every time this
40 * method is called. See <code>AbstractMap.values()</code> etc. Calling this
41 * method on the inverse map should return the original.
42 * <p>
43 * Implementations must return an <code>OrderedBidiMap</code> instance,
44 * usually by forwarding to <code>inverseOrderedBidiMap()</code>.
45 *
46 * @return an inverted bidirectional map
47 */
48 public BidiMap inverseBidiMap();
49
50 /**
51 * Gets a view of this map where the keys and values are reversed.
52 * <p>
53 * Changes to one map will be visible in the other and vice versa.
54 * This enables both directions of the map to be accessed equally.
55 * <p>
56 * Implementations should seek to avoid creating a new object every time this
57 * method is called. See <code>AbstractMap.values()</code> etc. Calling this
58 * method on the inverse map should return the original.
59 *
60 * @return an inverted bidirectional map
61 */
62 public OrderedBidiMap inverseOrderedBidiMap();
63
64 }
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