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   * A {@code Multimap} that can hold duplicate key-value pairs and that maintains
29   * the insertion ordering of values for a given key. See the {@link Multimap}
30   * documentation for information common to all multimaps.
31   *
32   * <p>The {@link #get}, {@link #removeAll}, and {@link #replaceValues} methods
33   * each return a {@link List} of values. Though the method signature doesn't say
34   * so explicitly, the map returned by {@link #asMap} has {@code List} values.
35   * 
36   * <p>See the Guava User Guide article on <a href=
37   * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#Multimap">
38   * {@code Multimap}</a>.
39   *
40   * @author Jared Levy
41   * @since 2.0 (imported from Google Collections Library)
42   */
43  @GwtCompatible
44  public interface ListMultimap<K, V> extends Multimap<K, V> {
45    /**
46     * {@inheritDoc}
47     *
48     * <p>Because the values for a given key may have duplicates and follow the
49     * insertion ordering, this method returns a {@link List}, instead of the
50     * {@link java.util.Collection} specified in the {@link Multimap} interface.
51     */
52    @Override
53    List<V> get(@Nullable K key);
54  
55    /**
56     * {@inheritDoc}
57     *
58     * <p>Because the values for a given key may have duplicates and follow the
59     * insertion ordering, this method returns a {@link List}, instead of the
60     * {@link java.util.Collection} specified in the {@link Multimap} interface.
61     */
62    @Override
63    List<V> removeAll(@Nullable Object key);
64  
65    /**
66     * {@inheritDoc}
67     *
68     * <p>Because the values for a given key may have duplicates and follow the
69     * insertion ordering, this method returns a {@link List}, instead of the
70     * {@link java.util.Collection} specified in the {@link Multimap} interface.
71     */
72    @Override
73    List<V> replaceValues(K key, Iterable<? extends V> values);
74  
75    /**
76     * {@inheritDoc}
77     *
78     * <p><b>Note:</b> The returned map's values are guaranteed to be of type
79     * {@link List}. To obtain this map with the more specific generic type
80     * {@code Map<K, List<V>>}, call {@link Multimaps#asMap(ListMultimap)}
81     * instead.
82     */
83    @Override
84    Map<K, Collection<V>> asMap();
85  
86    /**
87     * Compares the specified object to this multimap for equality.
88     *
89     * <p>Two {@code ListMultimap} instances are equal if, for each key, they
90     * contain the same values in the same order. If the value orderings disagree,
91     * the multimaps will not be considered equal.
92     *
93     * <p>An empty {@code ListMultimap} is equal to any other empty {@code
94     * Multimap}, including an empty {@code SetMultimap}.
95     */
96    @Override
97    boolean equals(@Nullable Object obj);
98  }