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 javax.annotation.CheckForNull;
025import org.checkerframework.checker.nullness.qual.Nullable;
026
027/**
028 * A {@code Multimap} that can hold duplicate key-value pairs and that maintains the insertion
029 * ordering of values for a given key. See the {@link Multimap} documentation for information common
030 * to all multimaps.
031 *
032 * <p>The {@link #get}, {@link #removeAll}, and {@link #replaceValues} methods each return a {@link
033 * List} of values. Though the method signature doesn't say so explicitly, the map returned by
034 * {@link #asMap} has {@code List} values.
035 *
036 * <p>See the Guava User Guide article on <a href=
037 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
038 *
039 * @author Jared Levy
040 * @since 2.0
041 */
042@GwtCompatible
043public interface ListMultimap<K extends @Nullable Object, V extends @Nullable Object>
044    extends Multimap<K, V> {
045  /**
046   * {@inheritDoc}
047   *
048   * <p>Because the values for a given key may have duplicates and follow the insertion ordering,
049   * this method returns a {@link List}, instead of the {@link java.util.Collection} specified in
050   * the {@link Multimap} interface.
051   */
052  @Override
053  List<V> get(@ParametricNullness K key);
054
055  /**
056   * {@inheritDoc}
057   *
058   * <p>Because the values for a given key may have duplicates and follow the insertion ordering,
059   * this method returns a {@link List}, instead of the {@link java.util.Collection} specified in
060   * the {@link Multimap} interface.
061   */
062  @CanIgnoreReturnValue
063  @Override
064  List<V> removeAll(@CheckForNull Object key);
065
066  /**
067   * {@inheritDoc}
068   *
069   * <p>Because the values for a given key may have duplicates and follow the insertion ordering,
070   * this method returns a {@link List}, instead of the {@link java.util.Collection} specified in
071   * the {@link Multimap} interface.
072   */
073  @CanIgnoreReturnValue
074  @Override
075  List<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values);
076
077  /**
078   * {@inheritDoc}
079   *
080   * <p><b>Note:</b> The returned map's values are guaranteed to be of type {@link List}. To obtain
081   * this map with the more specific generic type {@code Map<K, List<V>>}, call {@link
082   * Multimaps#asMap(ListMultimap)} instead.
083   */
084  @Override
085  Map<K, Collection<V>> asMap();
086
087  /**
088   * Compares the specified object to this multimap for equality.
089   *
090   * <p>Two {@code ListMultimap} instances are equal if, for each key, they contain the same values
091   * in the same order. If the value orderings disagree, the multimaps will not be considered equal.
092   *
093   * <p>An empty {@code ListMultimap} is equal to any other empty {@code Multimap}, including an
094   * empty {@code SetMultimap}.
095   */
096  @Override
097  boolean equals(@CheckForNull Object obj);
098}