| org.apache.commons.collections.BidiMap
All known Subclasses: org.apache.commons.collections.bidimap.AbstractDualBidiMap, org.apache.commons.collections.bidimap.AbstractBidiMapDecorator,
| BidiMap | | public interface BidiMap extends IterableMap(Code) | | Defines a map that allows bidirectional lookup between key and values.
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
BidiMap.put method description for more information.
since:
Commons Collections 3.0
version:
$Revision: 155406 $ $Date: 2005-02-26 12:55:26 +0000 (Sat, 26 Feb 2005) $
author:
Stephen Colebourne |
| Method Summary | |
| Object | getKey(Object value)
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.
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. | | 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.
When adding a key-value pair, the value may already exist in the map
against a different key. | | Object | removeValue(Object value)
Removes the key-value pair that is currently mapped to the specified
value (optional operation). |
| getKey | | Object getKey(Object value)(Code) | | 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 - the value to find the key for the mapped key, or null if not found
throws:
ClassCastException - (optional) if the map limits the type of the value and the specified value is inappropriate
throws:
NullPointerException - (optional) if the map limits the values tonon-null and null was specified |
| inverseBidiMap | | BidiMap inverseBidiMap()(Code) | | 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.
an inverted bidirectional map |
| mapIterator | | MapIterator mapIterator()(Code) | | Obtains a MapIterator over the map.
A map iterator is an efficient way of iterating over maps.
It does not require that the map is stored using Map Entry objects
which can increase performance.
BidiMap map = new DualHashBidiMap();
MapIterator it = map.mapIterator();
while (it.hasNext()) {
Object key = it.next();
Object value = it.getValue();
it.setValue("newValue");
}
a map iterator |
| put | | Object put(Object key, Object value)(Code) | | 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 - the key to store
Parameters:
value - the value to store the previous value mapped to this key
throws:
UnsupportedOperationException - if the put method is not supported
throws:
ClassCastException - (optional) if the map limits the type of the value and the specified value is inappropriate
throws:
IllegalArgumentException - (optional) if the map limits the valuesin some way and the value was invalid
throws:
NullPointerException - (optional) if the map limits the values tonon-null and null was specified |
| removeValue | | Object removeValue(Object value)(Code) | | 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 - the value to find the key-value pair for the key that was removed, null if nothing removed
throws:
ClassCastException - (optional) if the map limits the type of the value and the specified value is inappropriate
throws:
NullPointerException - (optional) if the map limits the values tonon-null and null was specified
throws:
UnsupportedOperationException - if this method is not supportedby the implementation |
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