001/*
002 * Copyright (C) 2007 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package com.google.common.collect;
018
019import com.google.common.annotations.GwtCompatible;
020import com.google.errorprone.annotations.CanIgnoreReturnValue;
021import java.util.Collection;
022import java.util.List;
023import java.util.Map;
024import org.checkerframework.checker.nullness.compatqual.NullableDecl;
025
026/**
027 * A {@code Multimap} that can hold duplicate key-value pairs and that maintains the insertion
028 * ordering of values for a given key. See the {@link Multimap} documentation for information common
029 * to all multimaps.
030 *
031 * <p>The {@link #get}, {@link #removeAll}, and {@link #replaceValues} methods each return a {@link
032 * List} of values. Though the method signature doesn't say so explicitly, the map returned by
033 * {@link #asMap} has {@code List} values.
034 *
035 * <p>See the Guava User Guide article on <a href=
036 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
037 * Multimap}</a>.
038 *
039 * @author Jared Levy
040 * @since 2.0
041 */
042@GwtCompatible
043public interface ListMultimap<K, V> extends Multimap<K, V> {
044  /**
045   * {@inheritDoc}
046   *
047   * <p>Because the values for a given key may have duplicates and follow the insertion ordering,
048   * this method returns a {@link List}, instead of the {@link java.util.Collection} specified in
049   * the {@link Multimap} interface.
050   */
051  @Override
052  List<V> get(@NullableDecl K key);
053
054  /**
055   * {@inheritDoc}
056   *
057   * <p>Because the values for a given key may have duplicates and follow the insertion ordering,
058   * this method returns a {@link List}, instead of the {@link java.util.Collection} specified in
059   * the {@link Multimap} interface.
060   */
061  @CanIgnoreReturnValue
062  @Override
063  List<V> removeAll(@NullableDecl Object key);
064
065  /**
066   * {@inheritDoc}
067   *
068   * <p>Because the values for a given key may have duplicates and follow the insertion ordering,
069   * this method returns a {@link List}, instead of the {@link java.util.Collection} specified in
070   * the {@link Multimap} interface.
071   */
072  @CanIgnoreReturnValue
073  @Override
074  List<V> replaceValues(K key, Iterable<? extends V> values);
075
076  /**
077   * {@inheritDoc}
078   *
079   * <p><b>Note:</b> The returned map's values are guaranteed to be of type {@link List}. To obtain
080   * this map with the more specific generic type {@code Map<K, List<V>>}, call {@link
081   * Multimaps#asMap(ListMultimap)} instead.
082   */
083  @Override
084  Map<K, Collection<V>> asMap();
085
086  /**
087   * Compares the specified object to this multimap for equality.
088   *
089   * <p>Two {@code ListMultimap} instances are equal if, for each key, they contain the same values
090   * in the same order. If the value orderings disagree, the multimaps will not be considered equal.
091   *
092   * <p>An empty {@code ListMultimap} is equal to any other empty {@code Multimap}, including an
093   * empty {@code SetMultimap}.
094   */
095  @Override
096  boolean equals(@NullableDecl Object obj);
097}