    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    }