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.Collection;
20 import java.util.Set;
21
22 /**
23 * The "read" subset of the {@link java.util.Map} interface.
24 *
25 * @param <K> the type of the keys in this map
26 * @param <V> the type of the values in this map
27 *
28 * @since 4.0
29 * @see Put
30 */
31 public interface Get<K, V> {
32
33 /**
34 * @param key key whose presence in this map is to be tested
35 * @return {@code true} if this map contains a mapping for the specified
36 * key
37 * @see java.util.Map#containsKey(Object)
38 */
39 boolean containsKey(Object key);
40
41 /**
42 * @param value value whose presence in this map is to be tested
43 * @return {@code true} if this map maps one or more keys to the
44 * specified value
45 * @see java.util.Map#containsValue(Object)
46 */
47 boolean containsValue(Object value);
48
49 /**
50 * @return a set view of the mappings contained in this map
51 * @see java.util.Map#entrySet()
52 */
53 Set<java.util.Map.Entry<K, V>> entrySet();
54
55 /**
56 * @param key the key whose associated value is to be returned
57 * @return the value to which the specified key is mapped, or
58 * {@code null} if this map contains no mapping for the key
59 * @see java.util.Map#get(Object)
60 */
61 V get(Object key);
62
63 /**
64 * @return {@code true} if this map contains no key-value mappings
65 * @see java.util.Map#isEmpty()
66 */
67 boolean isEmpty();
68
69 /**
70 * @return a set view of the keys contained in this map
71 * @see java.util.Map#keySet()
72 */
73 Set<K> keySet();
74
75 /**
76 * @param key key whose mapping is to be removed from the map
77 * @return the previous value associated with {@code key}, or
78 * {@code null} if there was no mapping for {@code key}.
79 * @see java.util.Map#remove(Object)
80 */
81 V remove(Object key);
82
83 /**
84 * @return the number of key-value mappings in this map
85 * @see java.util.Map#size()
86 */
87 int size();
88
89 /**
90 * @return a collection view of the values contained in this map
91 * @see java.util.Map#values()
92 */
93 Collection<V> values();
94
95 }