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 * @author Jared Levy
037 * @since 2.0 (imported from Google Collections Library)
038 */
039 @GwtCompatible
040 public interface SetMultimap<K, V> extends Multimap<K, V> {
041 /**
042 * {@inheritDoc}
043 *
044 * <p>Because a {@code SetMultimap} has unique values for a given key, this
045 * method returns a {@link Set}, instead of the {@link java.util.Collection}
046 * specified in the {@link Multimap} interface.
047 */
048 @Override
049 Set<V> get(@Nullable K key);
050
051 /**
052 * {@inheritDoc}
053 *
054 * <p>Because a {@code SetMultimap} has unique values for a given key, this
055 * method returns a {@link Set}, instead of the {@link java.util.Collection}
056 * specified in the {@link Multimap} interface.
057 */
058 @Override
059 Set<V> removeAll(@Nullable Object key);
060
061 /**
062 * {@inheritDoc}
063 *
064 * <p>Because a {@code SetMultimap} has unique values for a given key, this
065 * method returns a {@link Set}, instead of the {@link java.util.Collection}
066 * specified in the {@link Multimap} interface.
067 *
068 * <p>Any duplicates in {@code values} will be stored in the multimap once.
069 */
070 @Override
071 Set<V> replaceValues(K key, Iterable<? extends V> values);
072
073 /**
074 * {@inheritDoc}
075 *
076 * <p>Because a {@code SetMultimap} has unique values for a given key, this
077 * method returns a {@link Set}, instead of the {@link java.util.Collection}
078 * specified in the {@link Multimap} interface.
079 */
080 @Override
081 Set<Map.Entry<K, V>> entries();
082
083 /**
084 * {@inheritDoc}
085 *
086 * <p>Though the method signature doesn't say so explicitly, the returned map
087 * has {@link Set} values.
088 */
089 @Override
090 Map<K, Collection<V>> asMap();
091
092 /**
093 * Compares the specified object to this multimap for equality.
094 *
095 * <p>Two {@code SetMultimap} instances are equal if, for each key, they
096 * contain the same values. Equality does not depend on the ordering of keys
097 * or values.
098 *
099 * <p>An empty {@code SetMultimap} is equal to any other empty {@code
100 * Multimap}, including an empty {@code ListMultimap}.
101 */
102 @Override
103 boolean equals(@Nullable Object obj);
104 }