001    /*
002     * Copyright (C) 2007 Google Inc.
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 (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      Set<V> get(@Nullable K key);
049    
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      Set<V> removeAll(@Nullable Object key);
058    
059      /**
060       * {@inheritDoc}
061       *
062       * <p>Because a {@code SetMultimap} has unique values for a given key, this
063       * method returns a {@link Set}, instead of the {@link java.util.Collection}
064       * specified in the {@link Multimap} interface.
065       *
066       * <p>Any duplicates in {@code values} will be stored in the multimap once.
067       */
068      Set<V> replaceValues(K key, Iterable<? extends V> values);
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      Set<Map.Entry<K, V>> entries();
078    
079      /**
080       * {@inheritDoc}
081       *
082       * <p>Though the method signature doesn't say so explicitly, the returned map
083       * has {@link Set} values.
084       */
085      Map<K, Collection<V>> asMap();
086    
087      /**
088       * Compares the specified object to this multimap for equality.
089       *
090       * <p>Two {@code SetMultimap} instances are equal if, for each key, they
091       * contain the same values. Equality does not depend on the ordering of keys
092       * or values.
093       */
094      boolean equals(@Nullable Object obj);
095    }