Package com.google.common.collect

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

  • All Implemented Interfaces:
    Multimap<K,​V>, SetMultimap<K,​V>, SortedSetMultimap<K,​V>, Serializable
    @GwtCompatible(serializable=true,
               emulated=true)
public class TreeMultimap<K extends @Nullable Object,​V extends @Nullable Object>
extends Object
    Implementation of Multimap whose keys and values are ordered by their natural ordering or by supplied comparators. In all cases, this implementation uses Comparable.compareTo(T) or Comparator.compare(T, T) instead of Object.equals(java.lang.Object) to determine equivalence of instances.

    Warning: The comparators or comparables used must be consistent with equals as explained by the Comparable class specification. Otherwise, the resulting multiset will violate the general contract of SetMultimap, which is specified in terms of Object.equals(java.lang.Object).

    The collections returned by keySet and asMap iterate through the keys according to the key comparator ordering or the natural ordering of the keys. Similarly, get, removeAll, and replaceValues return collections that iterate through the values according to the value comparator ordering or the natural ordering of the values. The collections generated by entries, keys, and values iterate across the keys according to the above key ordering, and for each key they iterate across the values according to the value ordering.

    The multimap does not store duplicate key-value pairs. Adding a new key-value pair equal to an existing key-value pair has no effect.

    Null keys and values are permitted (provided, of course, that the respective comparators support them). All optional multimap methods are supported, and all returned views are modifiable.

    This class is not threadsafe when any concurrent operations update the multimap. Concurrent read operations will work correctly. To allow concurrent update operations, wrap your multimap with a call to Multimaps.synchronizedSortedSetMultimap(com.google.common.collect.SortedSetMultimap<K, V>).

    See the Guava User Guide article on Multimap.

    Since:
    2.0
    Author:
    Jared Levy, Louis Wasserman
    See Also:
    Serialized Form

    • Method Detail

      • create

        public static <K extends @Nullable Object,​V extends @Nullable Object> TreeMultimap<K,​V> create​(Comparator<? super K> keyComparator,
                                                                                                           Comparator<? super V> valueComparator)
        Creates an empty TreeMultimap instance using explicit comparators. Neither comparator may be null; use Ordering.natural() to specify natural order.
        Parameters:
        keyComparator - the comparator that determines the key ordering
        valueComparator - the comparator that determines the value ordering

      • create

        public static <K extends Comparable,​V extends Comparable> TreeMultimap<K,​V> create​(Multimap<? extends K,​? extends V> multimap)
        Constructs a TreeMultimap, ordered by the natural ordering of its keys and values, with the same mappings as the specified multimap.
        Parameters:
        multimap - the multimap whose contents are copied to this multimap

      • keyComparator

        @Deprecated
public Comparator<? super K> keyComparator()
        Deprecated.
        Use ((NavigableSet<K>) multimap.keySet()).comparator() instead.
        Returns the comparator that orders the multimap keys.

      • valueComparator

        public Comparator<? super V> valueComparator()
        Description copied from interface: SortedSetMultimap
        Returns the comparator that orders the multimap values, with null indicating that natural ordering is used.

      • keySet

        public NavigableSet<K> keySet()
        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.

        Because a TreeMultimap has unique sorted keys, this method returns a NavigableSet, instead of the Set specified in the Multimap interface.

        Specified by:
        keySet in interface Multimap<K extends @Nullable Object,​V extends @Nullable Object>
        Since:
        14.0 (present with return type SortedSet since 2.0)

      • asMap

        public NavigableMap<K,​Collection<V>> asMap()
        Returns a map view that associates each key with the corresponding values in the multimap. Changes to the returned map, such as element removal, will update the underlying multimap. The map does not support setValue on its entries, put, or putAll.

        When passed a key that is present in the map, asMap().get(Object) has the same behavior as SortedSetMultimap.get(K), returning a live collection. When passed a key that is not present, however, asMap().get(Object) returns null instead of an empty collection.

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

        Because a TreeMultimap has unique sorted keys, this method returns a NavigableMap, instead of the Map specified in the Multimap interface.

        Specified by:
        asMap in interface Multimap<K extends @Nullable Object,​V extends @Nullable Object>
        Specified by:
        asMap in interface SetMultimap<K extends @Nullable Object,​V extends @Nullable Object>
        Specified by:
        asMap in interface SortedSetMultimap<K extends @Nullable Object,​V extends @Nullable Object>
        Since:
        14.0 (present with return type SortedMap since 2.0)

      • 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.

        Consequently, the values do not follow their natural ordering or the ordering of the value comparator.

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

      • entries

        public Set<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.

        Because a SetMultimap has unique values for a given key, this method returns a Set, instead of the Collection specified in the Multimap interface.

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

      • 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 if the method increased the size of the multimap, or false if the multimap already contained the key-value pair

      • 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>

      • 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

      • 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