Package com.google.common.collect

Class ImmutableSetMultimap<K,​V>

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      static class  ImmutableSetMultimap.Builder<K,​V>
      A builder for creating immutable SetMultimap instances, especially public static final multimaps ("constant multimaps").

    • Method Detail

      • toImmutableSetMultimap

        public static <T extends @Nullable java.lang.Object,​K,​V> java.util.stream.Collector<T,​?,​ImmutableSetMultimap<K,​V>> toImmutableSetMultimap​(java.util.function.Function<? super T,​? extends K> keyFunction,
                                                                                                                                                                        java.util.function.Function<? super T,​? extends V> valueFunction)
        Returns a Collector that accumulates elements into an ImmutableSetMultimap whose keys and values are the result of applying the provided mapping functions to the input elements.

        For streams with defined encounter order (as defined in the Ordering section of the java.util.stream Javadoc), that order is preserved, but entries are grouped by key.

        Example: 

        
 static final Multimap<Character, String> FIRST_LETTER_MULTIMAP =
     Stream.of("banana", "apple", "carrot", "asparagus", "cherry")
         .collect(toImmutableSetMultimap(str -> str.charAt(0), str -> str.substring(1)));

 // is equivalent to

 static final Multimap<Character, String> FIRST_LETTER_MULTIMAP =
     new ImmutableSetMultimap.Builder<Character, String>()
         .put('b', "anana")
         .putAll('a', "pple", "sparagus")
         .putAll('c', "arrot", "herry")
         .build();
        Since:
        21.0

      • flatteningToImmutableSetMultimap

        public static <T extends @Nullable java.lang.Object,​K,​V> java.util.stream.Collector<T,​?,​ImmutableSetMultimap<K,​V>> flatteningToImmutableSetMultimap​(java.util.function.Function<? super T,​? extends K> keyFunction,
                                                                                                                                                                                  java.util.function.Function<? super T,​? extends java.util.stream.Stream<? extends V>> valuesFunction)
        Returns a Collector accumulating entries into an ImmutableSetMultimap. Each input element is mapped to a key and a stream of values, each of which are put into the resulting Multimap, in the encounter order of the stream and the encounter order of the streams of values.

        Example: 

        
 static final ImmutableSetMultimap<Character, Character> FIRST_LETTER_MULTIMAP =
     Stream.of("banana", "apple", "carrot", "asparagus", "cherry")
         .collect(
             flatteningToImmutableSetMultimap(
                  str -> str.charAt(0),
                  str -> str.substring(1).chars().mapToObj(c -> (char) c));

 // is equivalent to

 static final ImmutableSetMultimap<Character, Character> FIRST_LETTER_MULTIMAP =
     ImmutableSetMultimap.<Character, Character>builder()
         .putAll('b', Arrays.asList('a', 'n', 'a', 'n', 'a'))
         .putAll('a', Arrays.asList('p', 'p', 'l', 'e'))
         .putAll('c', Arrays.asList('a', 'r', 'r', 'o', 't'))
         .putAll('a', Arrays.asList('s', 'p', 'a', 'r', 'a', 'g', 'u', 's'))
         .putAll('c', Arrays.asList('h', 'e', 'r', 'r', 'y'))
         .build();

 // after deduplication, the resulting multimap is equivalent to

 static final ImmutableSetMultimap<Character, Character> FIRST_LETTER_MULTIMAP =
     ImmutableSetMultimap.<Character, Character>builder()
         .putAll('b', Arrays.asList('a', 'n'))
         .putAll('a', Arrays.asList('p', 'l', 'e', 's', 'a', 'r', 'g', 'u'))
         .putAll('c', Arrays.asList('a', 'r', 'o', 't', 'h', 'e', 'y'))
         .build();
 
 }
        Since:
        21.0

      • of

        public static <K,​V> ImmutableSetMultimap<K,​V> of()
        Returns the empty multimap.

        Performance note: the instance returned is a singleton.

      • of

        public static <K,​V> ImmutableSetMultimap<K,​V> of​(K k1,
                                                             V v1)
        Returns an immutable multimap containing a single entry.

      • of

        public static <K,​V> ImmutableSetMultimap<K,​V> of​(K k1,
                                                             V v1,
                                                             K k2,
                                                             V v2)
        Returns an immutable multimap containing the given entries, in order. Repeated occurrences of an entry (according to Object.equals(java.lang.Object)) after the first are ignored.

      • of

        public static <K,​V> ImmutableSetMultimap<K,​V> of​(K k1,
                                                             V v1,
                                                             K k2,
                                                             V v2,
                                                             K k3,
                                                             V v3)
        Returns an immutable multimap containing the given entries, in order. Repeated occurrences of an entry (according to Object.equals(java.lang.Object)) after the first are ignored.

      • of

        public static <K,​V> ImmutableSetMultimap<K,​V> of​(K k1,
                                                             V v1,
                                                             K k2,
                                                             V v2,
                                                             K k3,
                                                             V v3,
                                                             K k4,
                                                             V v4)
        Returns an immutable multimap containing the given entries, in order. Repeated occurrences of an entry (according to Object.equals(java.lang.Object)) after the first are ignored.

      • of

        public static <K,​V> ImmutableSetMultimap<K,​V> of​(K k1,
                                                             V v1,
                                                             K k2,
                                                             V v2,
                                                             K k3,
                                                             V v3,
                                                             K k4,
                                                             V v4,
                                                             K k5,
                                                             V v5)
        Returns an immutable multimap containing the given entries, in order. Repeated occurrences of an entry (according to Object.equals(java.lang.Object)) after the first are ignored.

      • builderWithExpectedKeys

        public static <K,​V> ImmutableSetMultimap.Builder<K,​V> builderWithExpectedKeys​(int expectedKeys)
        Returns a new builder with a hint for how many distinct keys are expected to be added. The generated builder is equivalent to that returned by builder(), but may perform better if expectedKeys is a good estimate.
        Throws:
        java.lang.IllegalArgumentException - if expectedKeys is negative
        Since:
        33.3.0

      • copyOf

        public static <K,​V> ImmutableSetMultimap<K,​V> copyOf​(Multimap<? extends K,​? extends V> multimap)
        Returns an immutable set multimap containing the same mappings as multimap. The generated multimap's key and value orderings correspond to the iteration ordering of the multimap.asMap() view. Repeated occurrences of an entry in the multimap after the first are ignored.

        Despite the method name, this method attempts to avoid actually copying the data when it is safe to do so. The exact circumstances under which a copy will or will not be performed are undocumented and subject to change.

        Throws:
        java.lang.NullPointerException - if any key or value in multimap is null

      • copyOf

        public static <K,​V> ImmutableSetMultimap<K,​V> copyOf​(java.lang.Iterable<? extends java.util.Map.Entry<? extends K,​? extends V>> entries)
        Returns an immutable multimap containing the specified entries. The returned multimap iterates over keys in the order they were first encountered in the input, and the values for each key are iterated in the order they were encountered. If two values for the same key are equal, the first value encountered is used.
        Throws:
        java.lang.NullPointerException - if any key, value, or entry is null
        Since:
        19.0

      • get

        public ImmutableSet<V> get​(K key)
        Returns an immutable set of the values for the given key. If no mappings in the multimap have the provided key, an empty immutable set is returned. The values are in the same order as the parameters used to build this multimap.
        Specified by:
        get in interface Multimap<K,​V>
        Specified by:
        get in interface SetMultimap<K,​V>
        Specified by:
        get in class ImmutableMultimap<K,​V>

      • inverse

        public ImmutableSetMultimap<V,​K> inverse()
        Returns an immutable multimap which is the inverse of this one. For every key-value mapping in the original, the result will have a mapping with key and value reversed.

        Because an inverse of a set multimap cannot contain multiple pairs with the same key and value, this method returns an ImmutableSetMultimap rather than the ImmutableMultimap specified in the ImmutableMultimap class.

        Specified by:
        inverse in class ImmutableMultimap<K,​V>

      • replaceValues

        @CanIgnoreReturnValue
@Deprecated
public final ImmutableSet<V> replaceValues​(K key,
                                           java.lang.Iterable<? extends V> values)
        Deprecated.
        Unsupported operation.
        Guaranteed to throw an exception and leave the multimap unmodified.
        Specified by:
        replaceValues in interface Multimap<K,​V>
        Specified by:
        replaceValues in interface SetMultimap<K,​V>
        Overrides:
        replaceValues in class ImmutableMultimap<K,​V>
        Returns:
        the collection of replaced values, or an empty collection if no values were previously associated with the key. The collection may be modifiable, but updating it will have no effect on the multimap.
        Throws:
        java.lang.UnsupportedOperationException - always

      • isEmpty

        public boolean isEmpty()
        Description copied from interface: Multimap
        Returns true if this multimap contains no key-value pairs. Equivalent to size() == 0, but can in some cases be more efficient.
        Specified by:
        isEmpty in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>

      • containsEntry

        public boolean containsEntry​(@CheckForNull
                             java.lang.Object key,
                             @CheckForNull
                             java.lang.Object value)
        Description copied from interface: Multimap
        Returns true if this multimap contains at least one key-value pair with the key key and the value value.
        Specified by:
        containsEntry in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>

      • equals

        public boolean equals​(@CheckForNull
                      java.lang.Object object)
        Description copied from interface: Multimap
        Compares the specified object with this multimap for equality. Two multimaps are equal when their map views, as returned by Multimap.asMap(), are also equal.

        In general, two multimaps with identical key-value mappings may or may not be equal, depending on the implementation. For example, two SetMultimap instances with the same key-value mappings are equal, but equality of two ListMultimap instances depends on the ordering of the values for each key.

        A non-empty SetMultimap cannot be equal to a non-empty ListMultimap, since their Multimap.asMap() views contain unequal collections as values. However, any two empty multimaps are equal, because they both have empty Multimap.asMap() views.

        Specified by:
        equals in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>
        Overrides:
        equals in class java.lang.Object

      • hashCode

        public int hashCode()
        Returns the hash code for this multimap.

        The hash code of a multimap is defined as the hash code of the map view, as returned by Multimap.asMap().

        Specified by:
        hashCode in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>
        Overrides:
        hashCode in class java.lang.Object
        See Also:
        Map.hashCode()

      • toString

        public java.lang.String toString()
        Returns a string representation of the multimap, generated by calling toString on the map returned by Multimap.asMap().
        Overrides:
        toString in class java.lang.Object
        Returns:
        a string representation of the multimap