Package org.apache.commons.collections.bidimap

Class AbstractDualBidiMap

java.lang.Object
org.apache.commons.collections.bidimap.AbstractDualBidiMap
All Implemented Interfaces:
Map, BidiMap, IterableMap
Direct Known Subclasses:
DualHashBidiMap, DualTreeBidiMap
public abstract class AbstractDualBidiMap extends Object implements BidiMap
Abstract BidiMap implemented using two maps.

An implementation can be written simply by implementing the createMap method.

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

  • Field Details

    • maps

      protected final transient Map[] maps
      Delegate map array. The first map contains standard entries, and the second contains inverses.

    • inverseBidiMap

      protected transient BidiMap inverseBidiMap
      Inverse view of this map.

    • keySet

      protected transient Set keySet
      View of the keys.

    • values

      protected transient Collection values
      View of the values.

    • entrySet

      protected transient Set entrySet
      View of the entries.

  • Constructor Details

    • AbstractDualBidiMap

      protected AbstractDualBidiMap()
      Creates an empty map, initialised by createMap.

      This constructor remains in place for deserialization. All other usage is deprecated in favour of AbstractDualBidiMap(Map, Map).

    • AbstractDualBidiMap

      protected AbstractDualBidiMap(Map normalMap, Map reverseMap)
      Creates an empty map using the two maps specified as storage.

      The two maps must be a matching pair, normal and reverse. They will typically both be empty.

      Neither map is validated, so nulls may be passed in. If you choose to do this then the subclass constructor must populate the maps[] instance variable itself.

      Parameters:
      normalMap - the normal direction map
      reverseMap - the reverse direction map
      Since:
      Commons Collections 3.1

    • AbstractDualBidiMap

      protected AbstractDualBidiMap(Map normalMap, Map reverseMap, BidiMap inverseBidiMap)
      Constructs a map that decorates the specified maps, used by the subclass createBidiMap implementation.
      Parameters:
      normalMap - the normal direction map
      reverseMap - the reverse direction map
      inverseBidiMap - the inverse BidiMap

  • Method Details

    • createMap

      protected Map createMap()
      Deprecated.
      For constructors, use the new two map constructor. For deserialization, populate the maps array directly in readObject.
      Creates a new instance of the map used by the subclass to store data.

      This design is deeply flawed and has been deprecated. It relied on subclass data being used during a superclass constructor.

      Returns:
      the map to be used for internal storage

    • createBidiMap

      protected abstract BidiMap createBidiMap(Map normalMap, Map reverseMap, BidiMap inverseMap)
      Creates a new instance of the subclass.
      Parameters:
      normalMap - the normal direction map
      reverseMap - the reverse direction map
      inverseMap - this map, which is the inverse in the new map
      Returns:
      the inverse map

    • get

      public Object get(Object key)
      Specified by:
      get in interface Map

    • size

      public int size()
      Specified by:
      size in interface Map

    • isEmpty

      public boolean isEmpty()
      Specified by:
      isEmpty in interface Map

    • containsKey

      public boolean containsKey(Object key)
      Specified by:
      containsKey in interface Map

    • equals

      public boolean equals(Object obj)
      Specified by:
      equals in interface Map
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Specified by:
      hashCode in interface Map
      Overrides:
      hashCode in class Object

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • put

      public Object put(Object key, Object value)
      Description copied from interface: BidiMap
      Puts the key-value pair into the map, replacing any previous pair.

      When adding a key-value pair, the value may already exist in the map against a different key. That mapping is removed, to ensure that the value only occurs once in the inverse map. 

        BidiMap map1 = new DualHashBidiMap();
  map.put("A","B");  // contains A mapped to B, as per Map
  map.put("A","C");  // contains A mapped to C, as per Map
 
  BidiMap map2 = new DualHashBidiMap();
  map.put("A","B");  // contains A mapped to B, as per Map
  map.put("C","B");  // contains C mapped to B, key A is removed
      Specified by:
      put in interface BidiMap
      Specified by:
      put in interface Map
      Parameters:
      key - the key to store
      value - the value to store
      Returns:
      the previous value mapped to this key

    • putAll

      public void putAll(Map map)
      Specified by:
      putAll in interface Map

    • remove

      public Object remove(Object key)
      Specified by:
      remove in interface Map

    • clear

      public void clear()
      Specified by:
      clear in interface Map

    • containsValue

      public boolean containsValue(Object value)
      Specified by:
      containsValue in interface Map

    • mapIterator

      public MapIterator mapIterator()
      Obtains a MapIterator over the map. The iterator implements ResetableMapIterator. This implementation relies on the entrySet iterator.

      The setValue() methods only allow a new value to be set. If the value being set is already in the map, an IllegalArgumentException is thrown (as setValue cannot change the size of the map).

      Specified by:
      mapIterator in interface BidiMap
      Specified by:
      mapIterator in interface IterableMap
      Returns:
      a map iterator

    • getKey

      public Object getKey(Object value)
      Description copied from interface: BidiMap
      Gets the key that is currently mapped to the specified value.

      If the value is not contained in the map, null is returned.

      Implementations should seek to make this method perform equally as well as get(Object).

      Specified by:
      getKey in interface BidiMap
      Parameters:
      value - the value to find the key for
      Returns:
      the mapped key, or null if not found

    • removeValue

      public Object removeValue(Object value)
      Description copied from interface: BidiMap
      Removes the key-value pair that is currently mapped to the specified value (optional operation).

      If the value is not contained in the map, null is returned.

      Implementations should seek to make this method perform equally as well as remove(Object).

      Specified by:
      removeValue in interface BidiMap
      Parameters:
      value - the value to find the key-value pair for
      Returns:
      the key that was removed, null if nothing removed

    • inverseBidiMap

      public BidiMap inverseBidiMap()
      Description copied from interface: BidiMap
      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 Map.

      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:
      inverseBidiMap in interface BidiMap
      Returns:
      an inverted bidirectional map

    • keySet

      public Set keySet()
      Gets a keySet view of the map. Changes made on the view are reflected in the map. The set supports remove and clear but not add.
      Specified by:
      keySet in interface Map
      Returns:
      the keySet view

    • createKeySetIterator

      protected Iterator createKeySetIterator(Iterator iterator)
      Creates a key set iterator. Subclasses can override this to return iterators with different properties.
      Parameters:
      iterator - the iterator to decorate
      Returns:
      the keySet iterator

    • values

      public Collection values()
      Gets a values view of the map. Changes made on the view are reflected in the map. The set supports remove and clear but not add.
      Specified by:
      values in interface Map
      Returns:
      the values view

    • createValuesIterator

      protected Iterator createValuesIterator(Iterator iterator)
      Creates a values iterator. Subclasses can override this to return iterators with different properties.
      Parameters:
      iterator - the iterator to decorate
      Returns:
      the values iterator

    • entrySet

      public Set entrySet()
      Gets an entrySet view of the map. Changes made on the set are reflected in the map. The set supports remove and clear but not add.

      The Map Entry setValue() method only allow a new value to be set. If the value being set is already in the map, an IllegalArgumentException is thrown (as setValue cannot change the size of the map).

      Specified by:
      entrySet in interface Map
      Returns:
      the entrySet view

    • createEntrySetIterator

      protected Iterator createEntrySetIterator(Iterator iterator)
      Creates an entry set iterator. Subclasses can override this to return iterators with different properties.
      Parameters:
      iterator - the iterator to decorate
      Returns:
      the entrySet iterator