Package com.globalmentor.collections

Class DecoratorReverseMap<K,V>

java.lang.Object

com.globalmentor.collections.MapDecorator<K,V>

com.globalmentor.collections.DecoratorReverseMap<K,V>

Type Parameters:

K - The type of map key.

V - The type of map value.

The keys and values in this map have a one-to-one relationship. Associating multiple values with a key will likely result in errant functionality.

All Implemented Interfaces:

ReverseMap<K,V>, Map<K,V>

public class DecoratorReverseMap<K,V>
extends MapDecorator<K,V>
implements ReverseMap<K,V>

A map that also allows lookup of the map keys keyed to the values by decorating two maps.

Author:

Garret Wilson

Nested Class Summary

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

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

Field Summary

Fields inherited from class com.globalmentor.collections.MapDecorator

map

Constructor Summary

Constructors

Constructor	Description
DecoratorReverseMap(Map<K,V> map, Map<V,K> reverseMap)	Constructs a reverse map by decorating two other maps.

Method Summary

Modifier and Type	Method	Description
void	clear()
boolean	containsValue(Object value)
K	getKey(V value)	Returns the key that represents the given value.
V	put(K key, V value)
V	remove(Object key)
K	removeValue(V value)	Removes the mapping for a value from this map if it is present.

Methods inherited from class com.globalmentor.collections.MapDecorator

compute, computeIfAbsent, computeIfPresent, containsKey, entrySet, equals, forEach, get, getOrDefault, hashCode, isEmpty, keySet, merge, putAll, putIfAbsent, remove, replace, replace, replaceAll, size, values

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, containsKey, entrySet, equals, forEach, get, getOrDefault, hashCode, isEmpty, keySet, merge, putAll, putIfAbsent, remove, replace, replace, replaceAll, size, values

Constructor Details

DecoratorReverseMap

public DecoratorReverseMap(Map<K,V> map,
 Map<V,K> reverseMap)

Constructs a reverse map by decorating two other maps.

Parameters:

map - The main map to be decorated.

reverseMap - The map to contain reverse lookup values.

Throws:

NullPointerException - if the given map and/or reverse map is null.

Method Details

getKey

public K getKey(V value)

Returns the key that represents the given value.

Specified by:

getKey in interface ReverseMap<K,V>

Parameters:

value - The value whose associated key is to be returned.

Returns:

The key to which this map reverse maps the specified value, or null if the map contains no reverse mapping for this value.

See Also:

• containsValue(Object)

removeValue

public K removeValue(V value)

Description copied from interface: ReverseMap

Removes the mapping for a value from this map if it is present.

Specified by:

removeValue in interface ReverseMap<K,V>

Parameters:

value - The value whose mapping is to be removed from the map.

Returns:

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

containsValue

public boolean containsValue(Object value)

Specified by:

containsValue in interface Map<K,V>

Overrides:

containsValue in class MapDecorator<K,V>

Implementation Specification:

This version uses an internal reverse map to provide faster lookups than the default linear-time lookup.

put

public V put(K key,
 V value)

Specified by:

put in interface Map<K,V>

Overrides:

put in class MapDecorator<K,V>

remove

public V remove(Object key)

Specified by:

remove in interface Map<K,V>

Overrides:

remove in class MapDecorator<K,V>

clear

public void clear()

Specified by:

clear in interface Map<K,V>

Overrides:

clear in class MapDecorator<K,V>