1 /*
2 * Copyright (C) 2007 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
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
17 package com.google.common.collect;
18
19 import com.google.common.annotations.GwtCompatible;
20
21 import java.util.Collection;
22 import java.util.List;
23 import java.util.Map;
24
25 import javax.annotation.Nullable;
26
27 /**
28 * Basic implementation of the {@link ListMultimap} interface. It's a wrapper
29 * around {@link AbstractMapBasedMultimap} that converts the returned collections into
30 * {@code Lists}. The {@link #createCollection} method must return a {@code
31 * List}.
32 *
33 * @author Jared Levy
34 * @since 2.0 (imported from Google Collections Library)
35 */
36 @GwtCompatible
37 abstract class AbstractListMultimap<K, V>
38 extends AbstractMapBasedMultimap<K, V> implements ListMultimap<K, V> {
39 /**
40 * Creates a new multimap that uses the provided map.
41 *
42 * @param map place to store the mapping from each key to its corresponding
43 * values
44 */
45 protected AbstractListMultimap(Map<K, Collection<V>> map) {
46 super(map);
47 }
48
49 @Override abstract List<V> createCollection();
50
51 @Override
52 List<V> createUnmodifiableEmptyCollection() {
53 return ImmutableList.of();
54 }
55
56 // Following Javadoc copied from ListMultimap.
57
58 /**
59 * {@inheritDoc}
60 *
61 * <p>Because the values for a given key may have duplicates and follow the
62 * insertion ordering, this method returns a {@link List}, instead of the
63 * {@link Collection} specified in the {@link Multimap} interface.
64 */
65 @Override public List<V> get(@Nullable K key) {
66 return (List<V>) super.get(key);
67 }
68
69 /**
70 * {@inheritDoc}
71 *
72 * <p>Because the values for a given key may have duplicates and follow the
73 * insertion ordering, this method returns a {@link List}, instead of the
74 * {@link Collection} specified in the {@link Multimap} interface.
75 */
76 @Override public List<V> removeAll(@Nullable Object key) {
77 return (List<V>) super.removeAll(key);
78 }
79
80 /**
81 * {@inheritDoc}
82 *
83 * <p>Because the values for a given key may have duplicates and follow the
84 * insertion ordering, this method returns a {@link List}, instead of the
85 * {@link Collection} specified in the {@link Multimap} interface.
86 */
87 @Override public List<V> replaceValues(
88 @Nullable K key, Iterable<? extends V> values) {
89 return (List<V>) super.replaceValues(key, values);
90 }
91
92 /**
93 * Stores a key-value pair in the multimap.
94 *
95 * @param key key to store in the multimap
96 * @param value value to store in the multimap
97 * @return {@code true} always
98 */
99 @Override public boolean put(@Nullable K key, @Nullable V value) {
100 return super.put(key, value);
101 }
102
103 /**
104 * {@inheritDoc}
105 *
106 * <p>Though the method signature doesn't say so explicitly, the returned map
107 * has {@link List} values.
108 */
109 @Override public Map<K, Collection<V>> asMap() {
110 return super.asMap();
111 }
112
113 /**
114 * Compares the specified object to this multimap for equality.
115 *
116 * <p>Two {@code ListMultimap} instances are equal if, for each key, they
117 * contain the same values in the same order. If the value orderings disagree,
118 * the multimaps will not be considered equal.
119 */
120 @Override public boolean equals(@Nullable Object object) {
121 return super.equals(object);
122 }
123
124 private static final long serialVersionUID = 6588350623831699109L;
125 }