Package org.apache.commons.collections.bidimap

Class DualTreeBidiMap

  • All Implemented Interfaces:
    Serializable, Map, SortedMap, BidiMap, IterableMap, OrderedBidiMap, OrderedMap, SortedBidiMap
    public class DualTreeBidiMap
extends AbstractDualBidiMap
implements SortedBidiMap, Serializable
    Implementation of BidiMap that uses two TreeMap instances.

    The setValue() method on iterators will succeed only if the new value being set is not already in the bidimap.

    When considering whether to use this class, the TreeBidiMap class should also be considered. It implements the interface using a dedicated design, and does not store each object twice, which can save on memory use.

    NOTE: From Commons Collections 3.1, all subclasses will use TreeMap and the flawed createMap method is ignored.

    Since:
    Commons Collections 3.0
    Version:
    $Id: DualTreeBidiMap.java 646777 2008-04-10 12:33:15Z niallp $
    Author:
    Matthew Hawthorne, Stephen Colebourne
    See Also:
    Serialized Form

    • Field Detail

      • comparator

        protected final Comparator comparator
        The comparator to use

    • Constructor Detail

      • DualTreeBidiMap

        public DualTreeBidiMap()
        Creates an empty DualTreeBidiMap

      • DualTreeBidiMap

        public DualTreeBidiMap​(Map map)
        Constructs a DualTreeBidiMap and copies the mappings from specified Map.
        Parameters:
        map - the map whose mappings are to be placed in this map

      • DualTreeBidiMap

        public DualTreeBidiMap​(Comparator comparator)
        Constructs a DualTreeBidiMap using the specified Comparator.
        Parameters:
        comparator - the Comparator

      • DualTreeBidiMap

        protected DualTreeBidiMap​(Map normalMap,
                          Map reverseMap,
                          BidiMap inverseBidiMap)
        Constructs a DualTreeBidiMap that decorates the specified maps.
        Parameters:
        normalMap - the normal direction map
        reverseMap - the reverse direction map
        inverseBidiMap - the inverse BidiMap

    • Method Detail

      • createBidiMap

        protected BidiMap createBidiMap​(Map normalMap,
                                Map reverseMap,
                                BidiMap inverseMap)
        Creates a new instance of this object.
        Specified by:
        createBidiMap in class AbstractDualBidiMap
        Parameters:
        normalMap - the normal direction map
        reverseMap - the reverse direction map
        inverseMap - the inverse BidiMap
        Returns:
        new bidi map

      • firstKey

        public Object firstKey()
        Description copied from interface: OrderedMap
        Gets the first key currently in this map.
        Specified by:
        firstKey in interface OrderedMap
        Specified by:
        firstKey in interface SortedMap
        Returns:
        the first key currently in this map

      • lastKey

        public Object lastKey()
        Description copied from interface: OrderedMap
        Gets the last key currently in this map.
        Specified by:
        lastKey in interface OrderedMap
        Specified by:
        lastKey in interface SortedMap
        Returns:
        the last key currently in this map

      • nextKey

        public Object nextKey​(Object key)
        Description copied from interface: OrderedMap
        Gets the next key after the one specified.
        Specified by:
        nextKey in interface OrderedMap
        Parameters:
        key - the key to search for next from
        Returns:
        the next key, null if no match or at end

      • previousKey

        public Object previousKey​(Object key)
        Description copied from interface: OrderedMap
        Gets the previous key before the one specified.
        Specified by:
        previousKey in interface OrderedMap
        Parameters:
        key - the key to search for previous from
        Returns:
        the previous key, null if no match or at start

      • orderedMapIterator

        public OrderedMapIterator orderedMapIterator()
        Obtains an ordered map iterator.

        This implementation copies the elements to an ArrayList in order to provide the forward/backward behaviour.

        Specified by:
        orderedMapIterator in interface OrderedMap
        Returns:
        a new ordered map iterator

      • inverseSortedBidiMap

        public SortedBidiMap inverseSortedBidiMap()
        Description copied from interface: SortedBidiMap
        Gets a view of this map where the keys and values are reversed.

        Changes to one map will be visible in the other and vice versa. This enables both directions of the map to be accessed as a SortedMap.

        Implementations should seek to avoid creating a new object every time this method is called. See AbstractMap.values() etc. Calling this method on the inverse map should return the original.

        The inverse map returned by inverseBidiMap() should be the same object as returned by this method.

        Specified by:
        inverseSortedBidiMap in interface SortedBidiMap
        Returns:
        an inverted bidirectional map

      • inverseOrderedBidiMap

        public OrderedBidiMap inverseOrderedBidiMap()
        Description copied from interface: OrderedBidiMap
        Gets a view of this map where the keys and values are reversed.

        Changes to one map will be visible in the other and vice versa. This enables both directions of the map to be accessed equally.

        Implementations should seek to avoid creating a new object every time this method is called. See AbstractMap.values() etc. Calling this method on the inverse map should return the original.

        Specified by:
        inverseOrderedBidiMap in interface OrderedBidiMap
        Returns:
        an inverted bidirectional map