K - the type of the keys in the map
V - the type of the values in the map
public interface BidiMap<K,V> extends IterableMap<K ,V>
This extended Map represents a mapping where a key may lookup a value and a value may lookup a key with equal ease. This interface extends Map and so may be used anywhere a map is required. The interface provides an inverse map view, enabling full access to both directions of the BidiMap.
Implementations should allow a value to be looked up from a key and a key to be looked up from a value with equal performance.
This map enforces the restriction that there is a 1:1 relation between keys and values, meaning that multiple keys cannot map to the same value. This is required so that "inverting" the map results in a map without duplicate keys. See the put(K, V) method description for more information.
| Modifier and Type | Method and Description |
|---|---|
K |
getKey(Object
Gets the key that is currently mapped to the specified value.
|
BidiMap |
inverseBidiMap()
Gets a view of this map where the keys and values are reversed.
|
V |
put(K key, V value)
Puts the key-value pair into the map, replacing any previous pair.
|
K |
removeValue(Object
Removes the key-value pair that is currently mapped to the specified value (optional operation).
|
Set |
values()
Returns a
Set view of the values contained in this map.
|
clear, compute, computeIfAbsent, computeIfPresent, containsKey, containsValue, entrySet, equals, forEach, get, getOrDefault, hashCode, isEmpty, keySet, merge, putAll, putIfAbsent, remove, remove, replace, replace, replaceAll, sizemapIteratorcontainsKey, containsValue, entrySet, get, isEmpty, keySet, remove, sizeV put(K key, V value)
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
put in interface
Map<K,V>
put in interface
Put<K,V>
key - the key to store
value - the value to store
UnsupportedOperationException - if the
put method is not supported
ClassCastException - (optional) if the map limits the type of the value and the specified value is inappropriate
IllegalArgumentException - (optional) if the map limits the values in some way and the value was invalid
NullPointerException - (optional) if the map limits the values to non-null and null was specified
Map.put(Object, Object)
K getKey(Objectvalue)
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).
value - the value to find the key for
null if not found
ClassCastException - (optional) if the map limits the type of the value and the specified value is inappropriate
NullPointerException - (optional) if the map limits the values to non-null and null was specified
K removeValue(Objectvalue)
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).
value - the value to find the key-value pair for
null if nothing removed
ClassCastException - (optional) if the map limits the type of the value and the specified value is inappropriate
NullPointerException - (optional) if the map limits the values to non-null and null was specified
UnsupportedOperationException - if this method is not supported by the implementation
BidiMap<V ,K> inverseBidiMap()
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.
Set<V> values()
Set view of the values contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress (except through the iterator's own
remove operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the
Iterator.remove,
Collection.remove,
removeAll,
retainAll and
clear operations. It does not support the
add or
addAll operations.