org.apache.commons.collections.bidimap
Class AbstractDualBidiMap

java.lang.Object
  |
  +--org.apache.commons.collections.bidimap.AbstractDualBidiMap

All Implemented Interfaces:

BidiMap, IterableMap, Map

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,v 1.14 2004/06/22 21:54:35 scolebourne Exp $

Author:

Matthew Hawthorne, Stephen Colebourne

See Also:

DualHashBidiMap, DualTreeBidiMap

Nested Class Summary

protected static class	AbstractDualBidiMap.BidiMapIterator Inner class MapIterator.
protected static class	AbstractDualBidiMap.EntrySet Inner class EntrySet.
protected static class	AbstractDualBidiMap.EntrySetIterator Inner class EntrySetIterator.
protected static class	AbstractDualBidiMap.KeySet Inner class KeySet.
protected static class	AbstractDualBidiMap.KeySetIterator Inner class KeySetIterator.
protected static class	AbstractDualBidiMap.MapEntry Inner class MapEntry.
protected static class	AbstractDualBidiMap.Values Inner class Values.
protected static class	AbstractDualBidiMap.ValuesIterator Inner class ValuesIterator.
protected static class	AbstractDualBidiMap.View Inner class View.

Field Summary

protected Set	entrySet View of the entries.
protected BidiMap	inverseBidiMap Inverse view of this map.
protected Set	keySet View of the keys.
protected Map[]	maps Delegate map array.
protected Collection	values View of the values.

Constructor Summary

protected	AbstractDualBidiMap() Creates an empty map, initialised by createMap.
protected	AbstractDualBidiMap(Map normalMap, Map reverseMap) Creates an empty map using the two maps specified as storage.
protected	AbstractDualBidiMap(Map normalMap, Map reverseMap, BidiMap inverseBidiMap) Constructs a map that decorates the specified maps, used by the subclass createBidiMap implementation.

Method Summary

void	clear()
boolean	containsKey(Object key)
boolean	containsValue(Object value)
protected abstract BidiMap	createBidiMap(Map normalMap, Map reverseMap, BidiMap inverseMap) Creates a new instance of the subclass.
protected Iterator	createEntrySetIterator(Iterator iterator) Creates an entry set iterator.
protected Iterator	createKeySetIterator(Iterator iterator) Creates a key set iterator.
protected Map	createMap() Deprecated. For constructors, use the new two map constructor. For deserialization, populate the maps array directly in readObject.
protected Iterator	createValuesIterator(Iterator iterator) Creates a values iterator.
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.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

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 Detail

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 Detail

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

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

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