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 * https://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
18 package org.apache.commons.collections4;
19
20 /**
21 * Defines a map that allows bidirectional lookup between key and values and retains and provides access to an ordering.
22 * <p>
23 * Implementations should allow a value to be looked up from a key and a key to be looked up from a value with equal performance.
24 * </p>
25 *
26 * @param <K> The type of the keys in the map.
27 * @param <V> The type of the values in the map.
28 * @since 3.0
29 */
30 public interface OrderedBidiMap<K, V> extends BidiMap<K, V>, OrderedMap<K, V> {
31
32 /**
33 * Gets a view of this map where the keys and values are reversed.
34 * <p>
35 * Changes to one map will be visible in the other and vice versa. This enables both directions of the map to be accessed equally.
36 * </p>
37 * <p>
38 * Implementations should seek to avoid creating a new object every time this method is called. See {@code AbstractMap.values()} etc. Calling this method on
39 * the inverse map should return the original.
40 * </p>
41 * <p>
42 * Implementations must return an {@code OrderedBidiMap} instance, usually by forwarding to {@code inverseOrderedBidiMap()}.
43 * </p>
44 *
45 * @return An inverted bidirectional map.
46 */
47 @Override
48 OrderedBidiMap<V, K> inverseBidiMap();
49 }