Apache Commons Collections 4.4 · org.apache.commons.collections4.BidiMap

Method Summary

Modifier and Type	Method and Description
public K	Returns: the mapped key, or `null` if not found getKey(Object the value to find the key for value) Gets the key that is currently mapped to the specified value.
public BidiMap<V, K>	Returns: an inverted bidirectional map inverseBidiMap() Gets a view of this map where the keys and values are reversed.
public V	Returns: the previous value mapped to this key put(K the key to store key, V the value to store value) Redeclares java.util.Map.put, org.apache.commons.collections4.Put.put. Puts the key-value pair into the map, replacing any previous pair.
public K	Returns: the key that was removed, `null` if nothing removed removeValue(Object the value to find the key-value pair for value) Removes the key-value pair that is currently mapped to the specified value (optional operation).
public Set<V>	Returns: a set view of the values contained in this map values() Redeclares java.util.Map.values, org.apache.commons.collections4.Get.values. Returns a `Set` view of the values contained in this map.

Method Detail

getKey back to summary

getKey	back to summary
public K 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:Object the value to find the key for Returns:K the mapped key, or `null` if not found Exceptions 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

public K 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:Object: the value to find the key for

Returns:K

the mapped key, or null if not found

Exceptions

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

inverseBidiMap back to summary

inverseBidiMap	back to summary
public BidiMap<V, K> 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:BidiMap<V, K> an inverted bidirectional map

public BidiMap<V, K> 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:BidiMap<V, K>: an inverted bidirectional map

put back to summary

put	back to summary
public V put(K key, V value) Redeclares java.util.Map.put, org.apache.commons.collections4.Put.put. 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:K the key to store value:V the value to store Returns:V the previous value mapped to this key Annotations @Override Exceptions 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

public V put(K key, V value)

Redeclares java.util.Map.put, org.apache.commons.collections4.Put.put.

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:K: the key to store
value:V: the value to store

Returns:V

the previous value mapped to this key

Annotations

@Override

Exceptions

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

removeValue back to summary

removeValue	back to summary
public K 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:Object the value to find the key-value pair for Returns:K the key that was removed, `null` if nothing removed Exceptions 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

public K 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:Object: the value to find the key-value pair for

Returns:K

the key that was removed, null if nothing removed

Exceptions

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

values back to summary

values	back to summary
public Set<V> values() Redeclares java.util.Map.values, org.apache.commons.collections4.Get.values. Returns a `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. Returns:Set<V> a set view of the values contained in this map Annotations @Override

public Set<V> values()

Redeclares java.util.Map.values, org.apache.commons.collections4.Get.values.

Returns a 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.

Returns:Set<V>

a set view of the values contained in this map

Annotations

@Override

public Interface BidiMap<K, V>

Method Summary

Method Detail