public abstract class

AbstractDualBidiMap

extends Object
implements BidiMap
java.lang.Object
   ↳ org.apache.commons.collections.bidimap.AbstractDualBidiMap
Known Direct Subclasses

Class Overview

Abstract BidiMap implemented using two maps.

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

See Also

Summary

Nested Classes
class AbstractDualBidiMap.BidiMapIterator Inner class MapIterator. 
class AbstractDualBidiMap.EntrySet Inner class EntrySet. 
class AbstractDualBidiMap.EntrySetIterator Inner class EntrySetIterator. 
class AbstractDualBidiMap.KeySet Inner class KeySet. 
class AbstractDualBidiMap.KeySetIterator Inner class KeySetIterator. 
class AbstractDualBidiMap.MapEntry Inner class MapEntry. 
class AbstractDualBidiMap.Values Inner class Values. 
class AbstractDualBidiMap.ValuesIterator Inner class ValuesIterator. 
class AbstractDualBidiMap.View Inner class View. 
Fields
protected Set entrySet View of the entries.
protected BidiMap inverseBidiMap Inverse view of this map.
protected Set keySet View of the keys.
protected final Map[] maps Delegate map array.
protected Collection values View of the values.
Protected Constructors
AbstractDualBidiMap()
Creates an empty map, initialised by createMap.
AbstractDualBidiMap(Map normalMap, Map reverseMap)
Creates an empty map using the two maps specified as storage.
AbstractDualBidiMap(Map normalMap, Map reverseMap, BidiMap inverseBidiMap)
Constructs a map that decorates the specified maps, used by the subclass createBidiMap implementation.
Public Methods
void clear()
boolean containsKey(Object key)
boolean containsValue(Object value)
Set entrySet()
Gets an entrySet view of the map.
boolean equals(Object obj)
Object get(Object key)
Object getKey(Object value)
Gets the key that is currently mapped to the specified value.
int hashCode()
BidiMap inverseBidiMap()
Gets a view of this map where the keys and values are reversed.
boolean isEmpty()
Set keySet()
Gets a keySet view of the map.
MapIterator mapIterator()
Obtains a MapIterator over the map.
Object put(Object key, Object value)
Puts the key-value pair into the map, replacing any previous pair.
void putAll(Map map)
Object remove(Object key)
Object removeValue(Object value)
Removes the key-value pair that is currently mapped to the specified value (optional operation).
int size()
String toString()
Collection values()
Gets a values view of the map.
Protected Methods
abstract BidiMap createBidiMap(Map normalMap, Map reverseMap, BidiMap inverseMap)
Creates a new instance of the subclass.
Iterator createEntrySetIterator(Iterator iterator)
Creates an entry set iterator.
Iterator createKeySetIterator(Iterator iterator)
Creates a key set iterator.
Map createMap()
This method is deprecated. For constructors, use the new two map constructor. For deserialization, populate the maps array directly in readObject.
Iterator createValuesIterator(Iterator iterator)
Creates a values iterator.
[Expand]
Inherited Methods
From class java.lang.Object
From interface java.util.Map
From interface org.apache.commons.collections.BidiMap
From interface org.apache.commons.collections.IterableMap

Fields

protected Set entrySet

View of the entries.

protected BidiMap inverseBidiMap

Inverse view of this map.

protected Set keySet

View of the keys.

protected final Map[] maps

Delegate map array. The first map contains standard entries, and the second contains inverses.

protected Collection values

View of the values.

Protected Constructors

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).

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

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

Public Methods

public void clear ()

public boolean containsKey (Object key)

public boolean containsValue (Object value)

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).

Returns
  • the entrySet view

public boolean equals (Object obj)

public Object get (Object key)

public Object getKey (Object value)

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).

Parameters
value the value to find the key for
Returns
  • the mapped key, or null if not found

public int hashCode ()

public BidiMap inverseBidiMap ()

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.

Returns
  • an inverted bidirectional map

public boolean isEmpty ()

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.

Returns
  • the keySet view

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).

Returns
  • a map iterator

public Object put (Object key, Object value)

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

Parameters
key the key to store
value the value to store
Returns
  • the previous value mapped to this key

public void putAll (Map map)

public Object remove (Object key)

public Object removeValue (Object value)

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).

Parameters
value the value to find the key-value pair for
Returns
  • the key that was removed, null if nothing removed

public int size ()

public String toString ()

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.

Returns
  • the values view

Protected Methods

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

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

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

protected Map createMap ()

This method is 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

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