Package com.google.common.collect

Class ArrayListMultimap<K extends @Nullable Object,​V extends @Nullable Object>

    • Method Detail

      • create

        public static <K extends @Nullable Object,​V extends @Nullable Object> ArrayListMultimap<K,​V> create()
        Creates a new, empty ArrayListMultimap with the default initial capacities.

        This method will soon be deprecated in favor of MultimapBuilder.hashKeys().arrayListValues().build().

      • create

        public static <K extends @Nullable Object,​V extends @Nullable Object> ArrayListMultimap<K,​V> create​(int expectedKeys,
                                                                                                                int expectedValuesPerKey)
        Constructs an empty ArrayListMultimap with enough capacity to hold the specified numbers of keys and values without resizing.

        This method will soon be deprecated in favor of MultimapBuilder.hashKeys(expectedKeys).arrayListValues(expectedValuesPerKey).build().

        Parameters:
        expectedKeys - the expected number of distinct keys
        expectedValuesPerKey - the expected average number of values per key
        Throws:
        IllegalArgumentException - if expectedKeys or expectedValuesPerKey is negative

      • create

        public static <K extends @Nullable Object,​V extends @Nullable Object> ArrayListMultimap<K,​V> create​(Multimap<? extends K,​? extends V> multimap)
        Constructs an ArrayListMultimap with the same mappings as the specified multimap.

        This method will soon be deprecated in favor of MultimapBuilder.hashKeys().arrayListValues().build(multimap).

        Parameters:
        multimap - the multimap whose contents are copied to this multimap

      • trimToSize

        @Deprecated
public void trimToSize()
        Deprecated.
        For a ListMultimap that automatically trims to size, use ImmutableListMultimap. If you need a mutable collection, remove the trimToSize call, or switch to a HashMap<K, ArrayList<V>>.
        Reduces the memory used by this ArrayListMultimap, if feasible.

      • get

        public List<V> get​(K key)
        Returns a view collection of the values associated with key in this multimap, if any. Note that when containsKey(key) is false, this returns an empty collection, not null.

        Changes to the returned collection will update the underlying multimap, and vice versa.

        The returned collection is not serializable.

        Because the values for a given key may have duplicates and follow the insertion ordering, this method returns a List, instead of the Collection specified in the Multimap interface.

        Specified by:
        get in interface ListMultimap<K extends @Nullable Object,​V extends @Nullable Object>
        Specified by:
        get in interface Multimap<K extends @Nullable Object,​V extends @Nullable Object>

      • replaceValues

        @CanIgnoreReturnValue
public List<V> replaceValues​(K key,
                             Iterable<? extends V> values)
        Stores a collection of values with the same key, replacing any existing values for that key.

        If values is empty, this is equivalent to removeAll(key).

        The returned collection is immutable.

        Because the values for a given key may have duplicates and follow the insertion ordering, this method returns a List, instead of the Collection specified in the Multimap interface.

        Specified by:
        replaceValues in interface ListMultimap<K extends @Nullable Object,​V extends @Nullable Object>
        Specified by:
        replaceValues in interface Multimap<K extends @Nullable Object,​V extends @Nullable Object>
        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.

      • put

        @CanIgnoreReturnValue
public boolean put​(K key,
                   V value)
        Stores a key-value pair in the multimap.
        Specified by:
        put in interface Multimap<K extends @Nullable Object,​V extends @Nullable Object>
        Parameters:
        key - key to store in the multimap
        value - value to store in the multimap
        Returns:
        true always

      • asMap

        public Map<K,​Collection<V>> asMap()
        Returns a view of this multimap as a Map from each distinct key to the nonempty collection of that key's associated values. Note that this.asMap().get(k) is equivalent to this.get(k) only when k is a key contained in the multimap; otherwise it returns null as opposed to an empty collection.

        Changes to the returned map or the collections that serve as its values will update the underlying multimap, and vice versa. The map does not support put or putAll, nor do its entries support setValue.

        Though the method signature doesn't say so explicitly, the returned map has List values.

        Specified by:
        asMap in interface ListMultimap<K extends @Nullable Object,​V extends @Nullable Object>
        Specified by:
        asMap in interface Multimap<K extends @Nullable Object,​V extends @Nullable Object>

      • equals

        public boolean equals​(@CheckForNull
                      Object object)
        Compares the specified object to this multimap for equality.

        Two ListMultimap instances are equal if, for each key, they contain the same values in the same order. If the value orderings disagree, the multimaps will not be considered equal.

        Specified by:
        equals in interface ListMultimap<K extends @Nullable Object,​V extends @Nullable Object>
        Specified by:
        equals in interface Multimap<K extends @Nullable Object,​V extends @Nullable 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

      • 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 extends @Nullable Object,​V extends @Nullable Object>

      • values

        public Collection<V> values()
        Returns a view collection containing the value from each key-value pair contained in this multimap, without collapsing duplicates (so values().size() == size()).

        Changes to the returned collection will update the underlying multimap, and vice versa. However, adding to the returned collection is not possible.

        The iterator generated by the returned collection traverses the values for one key, followed by the values of a second key, and so on.

        Specified by:
        values in interface Multimap<K extends @Nullable Object,​V extends @Nullable Object>

      • entries

        public Collection<Map.Entry<K,​V>> entries()
        Returns a view collection of all key-value pairs contained in this multimap, as Map.Entry instances.

        Changes to the returned collection or the entries it contains will update the underlying multimap, and vice versa. However, adding to the returned collection is not possible.

        The iterator generated by the returned collection traverses the values for one key, followed by the values of a second key, and so on.

        Each entry is an immutable snapshot of a key-value mapping in the multimap, taken at the time the entry is returned by a method call to the collection or its iterator.

        Specified by:
        entries in interface Multimap<K extends @Nullable Object,​V extends @Nullable Object>

      • 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 extends @Nullable Object,​V extends @Nullable Object>

      • 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>

      • putAll

        @CanIgnoreReturnValue
public boolean putAll​(K key,
                      Iterable<? extends V> values)
        Description copied from interface: Multimap
        Stores a key-value pair in this multimap for each of values, all using the same key, key. Equivalent to (but expected to be more efficient than): 
        
 for (V value : values) {
   put(key, value);
 }

        In particular, this is a no-op if values is empty.

        Specified by:
        putAll in interface Multimap<K extends @Nullable Object,​V extends @Nullable Object>
        Returns:
        true if the multimap changed

      • keySet

        public Set<K> keySet()
        Description copied from interface: Multimap
        Returns a view collection of all distinct keys contained in this multimap. Note that the key set contains a key if and only if this multimap maps that key to at least one value.

        Changes to the returned set will update the underlying multimap, and vice versa. However, adding to the returned set is not possible.

        Specified by:
        keySet in interface Multimap<K extends @Nullable Object,​V extends @Nullable Object>

      • keys

        public Multiset<K> keys()
        Description copied from interface: Multimap
        Returns a view collection containing the key from each key-value pair in this multimap, without collapsing duplicates. This collection has the same size as this multimap, and keys().count(k) == get(k).size() for all k.

        Changes to the returned multiset will update the underlying multimap, and vice versa. However, adding to the returned collection is not possible.

        Specified by:
        keys in interface Multimap<K extends @Nullable Object,​V extends @Nullable Object>

      • 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