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
017 package com.google.common.collect;
018
019 import com.google.common.annotations.GwtCompatible;
020
021 import java.util.Collection;
022 import java.util.Map;
023 import java.util.Set;
024
025 import javax.annotation.Nullable;
026
027 /**
028 * A {@code Multimap} that cannot hold duplicate key-value pairs. Adding a
029 * key-value pair that's already in the multimap has no effect.
030 *
031 * <p>The {@link #get}, {@link #removeAll}, and {@link #replaceValues} methods
032 * each return a {@link Set} of values, while {@link #entries} returns a {@code
033 * Set} of map entries. Though the method signature doesn't say so explicitly,
034 * the map returned by {@link #asMap} has {@code Set} values.
035 *
036 * <p>See the Guava User Guide article on <a href=
037 * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#Multimap">
038 * {@code Multimap}</a>.
039 *
040 * @author Jared Levy
041 * @since 2.0 (imported from Google Collections Library)
042 */
043 @GwtCompatible
044 public interface SetMultimap<K, V> extends Multimap<K, V> {
045 /**
046 * {@inheritDoc}
047 *
048 * <p>Because a {@code SetMultimap} has unique values for a given key, this
049 * method returns a {@link Set}, instead of the {@link java.util.Collection}
050 * specified in the {@link Multimap} interface.
051 */
052 @Override
053 Set<V> get(@Nullable K key);
054
055 /**
056 * {@inheritDoc}
057 *
058 * <p>Because a {@code SetMultimap} has unique values for a given key, this
059 * method returns a {@link Set}, instead of the {@link java.util.Collection}
060 * specified in the {@link Multimap} interface.
061 */
062 @Override
063 Set<V> removeAll(@Nullable Object key);
064
065 /**
066 * {@inheritDoc}
067 *
068 * <p>Because a {@code SetMultimap} has unique values for a given key, this
069 * method returns a {@link Set}, instead of the {@link java.util.Collection}
070 * specified in the {@link Multimap} interface.
071 *
072 * <p>Any duplicates in {@code values} will be stored in the multimap once.
073 */
074 @Override
075 Set<V> replaceValues(K key, Iterable<? extends V> values);
076
077 /**
078 * {@inheritDoc}
079 *
080 * <p>Because a {@code SetMultimap} has unique values for a given key, this
081 * method returns a {@link Set}, instead of the {@link java.util.Collection}
082 * specified in the {@link Multimap} interface.
083 */
084 @Override
085 Set<Map.Entry<K, V>> entries();
086
087 /**
088 * {@inheritDoc}
089 *
090 * <p>Though the method signature doesn't say so explicitly, the returned map
091 * has {@link Set} values.
092 */
093 @Override
094 Map<K, Collection<V>> asMap();
095
096 /**
097 * Compares the specified object to this multimap for equality.
098 *
099 * <p>Two {@code SetMultimap} instances are equal if, for each key, they
100 * contain the same values. Equality does not depend on the ordering of keys
101 * or values.
102 *
103 * <p>An empty {@code SetMultimap} is equal to any other empty {@code
104 * Multimap}, including an empty {@code ListMultimap}.
105 */
106 @Override
107 boolean equals(@Nullable Object obj);
108 }