1 /* 2 * Copyright (C) 2007 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.common.collect; 18 19 import com.google.common.annotations.GwtCompatible; 20 21 import java.util.Collection; 22 import java.util.Map; 23 import java.util.Set; 24 25 import javax.annotation.Nullable; 26 27 /** 28 * A {@code Multimap} that cannot hold duplicate key-value pairs. Adding a 29 * key-value pair that's already in the multimap has no effect. See the {@link 30 * Multimap} documentation for information common to all multimaps. 31 * 32 * <p>The {@link #get}, {@link #removeAll}, and {@link #replaceValues} methods 33 * each return a {@link Set} of values, while {@link #entries} returns a {@code 34 * Set} of map entries. Though the method signature doesn't say so explicitly, 35 * the map returned by {@link #asMap} has {@code Set} values. 36 * 37 * <p>If the values corresponding to a single key should be ordered according to 38 * a {@link java.util.Comparator} (or the natural order), see the 39 * {@link SortedSetMultimap} subinterface. 40 * 41 * <p>Since the value collections are sets, the behavior of a {@code SetMultimap} 42 * is not specified if key <em>or value</em> objects already present in the 43 * multimap change in a manner that affects {@code equals} comparisons. 44 * Use caution if mutable objects are used as keys or values in a 45 * {@code SetMultimap}. 46 * 47 * <p>See the Guava User Guide article on <a href= 48 * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#Multimap"> 49 * {@code Multimap}</a>. 50 * 51 * @author Jared Levy 52 * @since 2.0 (imported from Google Collections Library) 53 */ 54 @GwtCompatible 55 public interface SetMultimap<K, V> extends Multimap<K, V> { 56 /** 57 * {@inheritDoc} 58 * 59 * <p>Because a {@code SetMultimap} has unique values for a given key, this 60 * method returns a {@link Set}, instead of the {@link java.util.Collection} 61 * specified in the {@link Multimap} interface. 62 */ 63 @Override get(@ullable K key)64 Set<V> get(@Nullable K key); 65 66 /** 67 * {@inheritDoc} 68 * 69 * <p>Because a {@code SetMultimap} has unique values for a given key, this 70 * method returns a {@link Set}, instead of the {@link java.util.Collection} 71 * specified in the {@link Multimap} interface. 72 */ 73 @Override removeAll(@ullable Object key)74 Set<V> removeAll(@Nullable Object key); 75 76 /** 77 * {@inheritDoc} 78 * 79 * <p>Because a {@code SetMultimap} has unique values for a given key, this 80 * method returns a {@link Set}, instead of the {@link java.util.Collection} 81 * specified in the {@link Multimap} interface. 82 * 83 * <p>Any duplicates in {@code values} will be stored in the multimap once. 84 */ 85 @Override replaceValues(K key, Iterable<? extends V> values)86 Set<V> replaceValues(K key, Iterable<? extends V> values); 87 88 /** 89 * {@inheritDoc} 90 * 91 * <p>Because a {@code SetMultimap} has unique values for a given key, this 92 * method returns a {@link Set}, instead of the {@link java.util.Collection} 93 * specified in the {@link Multimap} interface. 94 */ 95 @Override entries()96 Set<Map.Entry<K, V>> entries(); 97 98 /** 99 * {@inheritDoc} 100 * 101 * <p><b>Note:</b> The returned map's values are guaranteed to be of type 102 * {@link Set}. To obtain this map with the more specific generic type 103 * {@code Map<K, Set<V>>}, call {@link Multimaps#asMap(SetMultimap)} instead. 104 */ 105 @Override asMap()106 Map<K, Collection<V>> asMap(); 107 108 /** 109 * Compares the specified object to this multimap for equality. 110 * 111 * <p>Two {@code SetMultimap} instances are equal if, for each key, they 112 * contain the same values. Equality does not depend on the ordering of keys 113 * or values. 114 * 115 * <p>An empty {@code SetMultimap} is equal to any other empty {@code 116 * Multimap}, including an empty {@code ListMultimap}. 117 */ 118 @Override equals(@ullable Object obj)119 boolean equals(@Nullable Object obj); 120 } 121