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    }