Package com.google.common.collect

Class ImmutableSetMultimap<K,​V>

    • Method Detail

      • toImmutableSetMultimap

        public static <T extends @Nullable Object,​K,​V> Collector<T,​?,​ImmutableSetMultimap<K,​V>> toImmutableSetMultimap​(Function<? super T,​? extends K> keyFunction,
                                                                                                                                             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 Object,​K,​V> Collector<T,​?,​ImmutableSetMultimap<K,​V>> flatteningToImmutableSetMultimap​(Function<? super T,​? extends K> keyFunction,
                                                                                                                                                       Function<? super T,​? extends 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.

      • 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:
        NullPointerException - if any key or value in multimap is null

      • copyOf

        @Beta
public static <K,​V> ImmutableSetMultimap<K,​V> copyOf​(Iterable<? extends 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:
        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>

      • 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 Object,​V extends @Nullable Object>

      • equals

        public boolean equals​(@CheckForNull
                      Object object)
        Description copied from class: java.lang.Object
        Indicates whether some other object is "equal to" this one.

        The equals method implements an equivalence relation on non-null object references:

        • It is reflexive: for any non-null reference value x, x.equals(x) should return true.
        • It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
        • It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
        • It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
        • For any non-null reference value x, x.equals(null) should return false.

        The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).

        Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.

        Specified by:
        equals in interface Multimap<K extends @Nullable Object,​V extends @Nullable Object>
        Overrides:
        equals in class Object
        Parameters:
        object - the reference object with which to compare.
        Returns:
        true if this object is the same as the obj argument; false otherwise.
        See Also:
        Object.hashCode(), HashMap

      • toString

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