Package org.apache.commons.collections4.bidimap

Class AbstractDualBidiMap<K,V>

java.lang.Object

org.apache.commons.collections4.bidimap.AbstractDualBidiMap<K,V>

Type Parameters:

K - the type of the keys in the map

V - the type of the values in the map

All Implemented Interfaces:

Map<K,V>, BidiMap<K,V>, Get<K,V>, IterableGet<K,V>, IterableMap<K,V>, Put<K,V>

Direct Known Subclasses:

DualHashBidiMap, DualLinkedHashBidiMap, DualTreeBidiMap

public abstract class AbstractDualBidiMap<K,V>
extends Object
implements BidiMap<K,V>

Abstract BidiMap implemented using two maps.

An implementation can be written simply by implementing the createBidiMap(Map, Map, BidiMap) method.

Since:

3.0

See Also:

• DualHashBidiMap
• DualTreeBidiMap

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	AbstractDualBidiMap.BidiMapIterator<K,V>	Inner class MapIterator.
protected static class	AbstractDualBidiMap.EntrySet<K,V>	Inner class EntrySet.
protected static class	AbstractDualBidiMap.EntrySetIterator<K,V>	Inner class EntrySetIterator.
protected static class	AbstractDualBidiMap.KeySet<K>	Inner class KeySet.
protected static class	AbstractDualBidiMap.KeySetIterator<K>	Inner class KeySetIterator.
protected static class	AbstractDualBidiMap.MapEntry<K,V>	Inner class MapEntry.
protected static class	AbstractDualBidiMap.Values<V>	Inner class Values.
protected static class	AbstractDualBidiMap.ValuesIterator<V>	Inner class ValuesIterator.
protected static class	AbstractDualBidiMap.View<K,V,E>	Inner class View.

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K extends Object,V extends Object>

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractDualBidiMap()	Creates an empty map, initialized by createMap.
protected	AbstractDualBidiMap(Map<K,V> normalMap, Map<V,K> reverseMap)	Creates an empty map using the two maps specified as storage.
protected	AbstractDualBidiMap(Map<K,V> normalMap, Map<V,K> reverseMap, BidiMap<V,K> inverseBidiMap)	Constructs a map that decorates the specified maps, used by the subclass createBidiMap implementation.

Method Summary

Modifier and Type	Method	Description
void	clear()
boolean	containsKey(Object key)
boolean	containsValue(Object value)
protected abstract BidiMap<V,K>	createBidiMap(Map<V,K> normalMap, Map<K,V> reverseMap, BidiMap<K,V> inverseMap)	Creates a new instance of the subclass.
protected Iterator<Map.Entry<K,V>>	createEntrySetIterator(Iterator<Map.Entry<K,V>> iterator)	Creates an entry set iterator.
protected Iterator<K>	createKeySetIterator(Iterator<K> iterator)	Creates a key set iterator.
protected Iterator<V>	createValuesIterator(Iterator<V> iterator)	Creates a values iterator.
Set<Map.Entry<K,V>>	entrySet()	Gets an entrySet view of the map.
boolean	equals(Object obj)
V	get(Object key)
K	getKey(Object value)	Gets the key that is currently mapped to the specified value.
int	hashCode()
BidiMap<V,K>	inverseBidiMap()	Gets a view of this map where the keys and values are reversed.
boolean	isEmpty()
Set<K>	keySet()	Gets a keySet view of the map.
MapIterator<K,V>	mapIterator()	Obtains a MapIterator over the map.
V	put(K key, V value)	Puts the key-value pair into the map, replacing any previous pair.
void	putAll(Map<? extends K,? extends V> map)
V	remove(Object key)
K	removeValue(Object value)	Removes the key-value pair that is currently mapped to the specified value (optional operation).
int	size()
String	toString()
Set<V>	values()	Gets a values view of the map.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll

Constructor Details

AbstractDualBidiMap

protected AbstractDualBidiMap()

Creates an empty map, initialized by createMap.

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

AbstractDualBidiMap

protected AbstractDualBidiMap(Map<K,V> normalMap,
 Map<V,K> 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:

3.1

AbstractDualBidiMap

protected AbstractDualBidiMap(Map<K,V> normalMap,
 Map<V,K> reverseMap,
 BidiMap<V,K> 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

clear

public void clear()

Specified by:

clear in interface Map<K,V>

Specified by:

clear in interface Put<K,V>

See Also:

• Map.clear()

containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Get<K,V>

Specified by:

containsKey in interface Map<K,V>

Parameters:

key - key whose presence in this map is to be tested

Returns:

true if this map contains a mapping for the specified key

See Also:

• Map.containsKey(Object)

containsValue

public boolean containsValue(Object value)

Specified by:

containsValue in interface Get<K,V>

Specified by:

containsValue in interface Map<K,V>

Parameters:

value - value whose presence in this map is to be tested

Returns:

true if this map maps one or more keys to the specified value

See Also:

• Map.containsValue(Object)

createBidiMap

protected abstract BidiMap<V,K> createBidiMap(Map<V,K> normalMap,
 Map<K,V> reverseMap,
 BidiMap<K,V> 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 bidi map

createEntrySetIterator

protected Iterator<Map.Entry<K,V>> createEntrySetIterator(Iterator<Map.Entry<K,V>> 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

createKeySetIterator

protected Iterator<K> createKeySetIterator(Iterator<K> 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

createValuesIterator

protected Iterator<V> createValuesIterator(Iterator<V> 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<Map.Entry<K,V>> 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 Get<K,V>

Specified by:

entrySet in interface Map<K,V>

Returns:

the entrySet view

See Also:

• Map.entrySet()

equals

public boolean equals(Object obj)

Specified by:

equals in interface Map<K,V>

Overrides:

equals in class Object

get

public V get(Object key)

Specified by:

get in interface Get<K,V>

Specified by:

get in interface Map<K,V>

Parameters:

key - the key whose associated value is to be returned

Returns:

the value to which the specified key is mapped, or null if this map contains no mapping for the key

See Also:

• Map.get(Object)

getKey

public K 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<K,V>

Parameters:

value - the value to find the key for

Returns:

the mapped key, or null if not found

hashCode

public int hashCode()

Specified by:

hashCode in interface Map<K,V>

Overrides:

hashCode in class Object

inverseBidiMap

public BidiMap<V,K> 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<K,V>

Returns:

an inverted bidirectional map

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Get<K,V>

Specified by:

isEmpty in interface Map<K,V>

Returns:

true if this map contains no key-value mappings

See Also:

• Map.isEmpty()

keySet

public Set<K> 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 Get<K,V>

Specified by:

keySet in interface Map<K,V>

Returns:

the keySet view

See Also:

• Map.keySet()

mapIterator

public MapIterator<K,V> mapIterator()

Obtains a MapIterator over the map. The iterator implements AbstractDualBidiMap.BidiMapIterator. This implementation relies on the entrySet iterator.

Specified by:

mapIterator in interface IterableGet<K,V>

Returns:

a map iterator

put

public V put(K key,
 V 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<K,V>

Specified by:

put in interface Map<K,V>

Specified by:

put in interface Put<K,V>

Parameters:

key - the key to store

value - the value to store

Returns:

the previous value mapped to this key

See Also:

• Map.put(Object, Object)

putAll

public void putAll(Map<? extends K,? extends V> map)

Specified by:

putAll in interface Map<K,V>

Specified by:

putAll in interface Put<K,V>

Parameters:

map - mappings to be stored in this map

See Also:

• Map.putAll(Map)

remove

public V remove(Object key)

Specified by:

remove in interface Get<K,V>

Specified by:

remove in interface Map<K,V>

Parameters:

key - key whose mapping is to be removed from the map

Returns:

the previous value associated with key, or null if there was no mapping for key.

See Also:

• Map.remove(Object)

removeValue

public K 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<K,V>

Parameters:

value - the value to find the key-value pair for

Returns:

the key that was removed, null if nothing removed

size

public int size()

Specified by:

size in interface Get<K,V>

Specified by:

size in interface Map<K,V>

Returns:

the number of key-value mappings in this map

See Also:

• Map.size()

toString

public String toString()

Overrides:

toString in class Object

values

public Set<V> 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 BidiMap<K,V>

Specified by:

values in interface Get<K,V>

Specified by:

values in interface Map<K,V>

Returns:

the values view

See Also:

• Map.values()