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. See the {@link
030 * Multimap} documentation for information common to all multimaps.
031 *
032 * <p>The {@link #get}, {@link #removeAll}, and {@link #replaceValues} methods
033 * each return a {@link Set} of values, while {@link #entries} returns a {@code
034 * Set} of map entries. Though the method signature doesn't say so explicitly,
035 * the map returned by {@link #asMap} has {@code Set} values.
036 *
037 * <p>If the values corresponding to a single key should be ordered according to
038 * a {@link java.util.Comparator} (or the natural order), see the
039 * {@link SortedSetMultimap} subinterface.
040 *
041 * <p>See the Guava User Guide article on <a href=
042 * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#Multimap">
043 * {@code Multimap}</a>.
044 *
045 * @author Jared Levy
046 * @since 2.0 (imported from Google Collections Library)
047 */
048 @GwtCompatible
049 public interface SetMultimap<K, V> extends Multimap<K, V> {
050 /**
051 * {@inheritDoc}
052 *
053 * <p>Because a {@code SetMultimap} has unique values for a given key, this
054 * method returns a {@link Set}, instead of the {@link java.util.Collection}
055 * specified in the {@link Multimap} interface.
056 */
057 @Override
058 Set<V> get(@Nullable K key);
059
060 /**
061 * {@inheritDoc}
062 *
063 * <p>Because a {@code SetMultimap} has unique values for a given key, this
064 * method returns a {@link Set}, instead of the {@link java.util.Collection}
065 * specified in the {@link Multimap} interface.
066 */
067 @Override
068 Set<V> removeAll(@Nullable Object key);
069
070 /**
071 * {@inheritDoc}
072 *
073 * <p>Because a {@code SetMultimap} has unique values for a given key, this
074 * method returns a {@link Set}, instead of the {@link java.util.Collection}
075 * specified in the {@link Multimap} interface.
076 *
077 * <p>Any duplicates in {@code values} will be stored in the multimap once.
078 */
079 @Override
080 Set<V> replaceValues(K key, Iterable<? extends V> values);
081
082 /**
083 * {@inheritDoc}
084 *
085 * <p>Because a {@code SetMultimap} has unique values for a given key, this
086 * method returns a {@link Set}, instead of the {@link java.util.Collection}
087 * specified in the {@link Multimap} interface.
088 */
089 @Override
090 Set<Map.Entry<K, V>> entries();
091
092 /**
093 * {@inheritDoc}
094 *
095 * <p>Though the method signature doesn't say so explicitly, the returned map
096 * has {@link Set} values.
097 */
098 @Override
099 Map<K, Collection<V>> asMap();
100
101 /**
102 * Compares the specified object to this multimap for equality.
103 *
104 * <p>Two {@code SetMultimap} instances are equal if, for each key, they
105 * contain the same values. Equality does not depend on the ordering of keys
106 * or values.
107 *
108 * <p>An empty {@code SetMultimap} is equal to any other empty {@code
109 * Multimap}, including an empty {@code ListMultimap}.
110 */
111 @Override
112 boolean equals(@Nullable Object obj);
113 }