Package com.google.common.collect

Class ImmutableMultimap<K,​V>

    • Nested Class Summary

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

    • Method Detail

      • of

        public static <K,​V> ImmutableMultimap<K,​V> of()
        Returns an empty multimap.

        Performance note: the instance returned is a singleton.

      • of

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

      • of

        public static <K,​V> ImmutableMultimap<K,​V> of​(K k1,
                                                          V v1,
                                                          K k2,
                                                          V v2)
        Returns an immutable multimap containing the given entries, in order.

      • of

        public static <K,​V> ImmutableMultimap<K,​V> of​(K k1,
                                                          V v1,
                                                          K k2,
                                                          V v2,
                                                          K k3,
                                                          V v3)
        Returns an immutable multimap containing the given entries, in the "key-grouped" insertion order described in the class documentation.

      • of

        public static <K,​V> ImmutableMultimap<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 the "key-grouped" insertion order described in the class documentation.

      • of

        public static <K,​V> ImmutableMultimap<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 the "key-grouped" insertion order described in the class documentation.

      • copyOf

        public static <K,​V> ImmutableMultimap<K,​V> copyOf​(Multimap<? extends K,​? extends V> multimap)
        Returns an immutable multimap containing the same mappings as multimap, in the "key-grouped" iteration order described in the class documentation.

        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> ImmutableMultimap<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.
        Throws:
        NullPointerException - if any key, value, or entry is null
        Since:
        19.0

      • get

        public abstract ImmutableCollection<V> get​(K key)
        Returns an immutable collection of the values for the given key. If no mappings in the multimap have the provided key, an empty immutable collection 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>

      • inverse

        public abstract ImmutableMultimap<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.
        Since:
        11.0

      • put

        @CanIgnoreReturnValue
@Deprecated
public final boolean put​(K key,
                         V value)
        Deprecated.
        Unsupported operation.
        Guaranteed to throw an exception and leave the multimap unmodified.
        Specified by:
        put in interface Multimap<K,​V>
        Returns:
        true if the method increased the size of the multimap, or false if the multimap already contained the key-value pair and doesn't allow duplicates
        Throws:
        UnsupportedOperationException - always

      • size

        public int size()
        Description copied from interface: Multimap
        Returns the number of key-value pairs in this multimap.

        Note: this method does not return the number of distinct keys in the multimap, which is given by keySet().size() or asMap().size(). See the opening section of the Multimap class documentation for clarification.

        Specified by:
        size in interface Multimap<K,​V>

      • keySet

        public ImmutableSet<K> keySet()
        Returns an immutable set of the distinct keys in this multimap, in the same order as they appear in this multimap.
        Specified by:
        keySet in interface Multimap<K,​V>

      • asMap

        public ImmutableMap<K,​Collection<V>> asMap()
        Returns an immutable map that associates each key with its corresponding values in the multimap. Keys and values appear in the same order as in this multimap.
        Specified by:
        asMap in interface Multimap<K,​V>

      • forEach

        public void forEach​(BiConsumer<? super K,​? super V> action)
        Description copied from interface: Multimap
        Performs the given action for all key-value pairs contained in this multimap. If an ordering is specified by the Multimap implementation, actions will be performed in the order of iteration of Multimap.entries(). Exceptions thrown by the action are relayed to the caller.

        To loop over all keys and their associated value collections, write Multimaps.asMap(multimap).forEach((key, valueCollection) -> action()).

        Specified by:
        forEach in interface Multimap<K,​V>

      • keys

        public ImmutableMultiset<K> keys()
        Returns an immutable multiset containing all the keys in this multimap, in the same order and with the same frequencies as they appear in this multimap; to get only a single occurrence of each key, use keySet().
        Specified by:
        keys in interface Multimap<K,​V>

      • values

        public ImmutableCollection<V> values()
        Returns an immutable collection of the values in this multimap. Its iterator traverses the values for the first key, the values for the second key, and so on.
        Specified by:
        values in interface Multimap<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