com.google.common.collect

Interface BiMap<K,V>

All Superinterfaces:

Map<K,V>

All Known Implementing Classes:

EnumBiMap, EnumHashBiMap, HashBiMap, ImmutableBiMap

@GwtCompatible
public interface BiMap<K,V>
extends Map<K,V>

A bimap (or "bidirectional map") is a map that preserves the uniqueness of its values as well as that of its keys. This constraint enables bimaps to support an "inverse view", which is another bimap containing the same entries as this bimap but with reversed keys and values.

See the Guava User Guide article on BiMap.

Since:

2.0

Author:

Kevin Bourrillion

Nested Class Summary

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

Map.Entry<K,V>

Method Summary

Modifier and Type	Method and Description
V	forcePut(K key, V value) An alternate form of put that silently removes any existing entry with the value value before proceeding with the put(K, V) operation.
BiMap<V,K>	inverse() Returns the inverse view of this bimap, which maps each of this bimap's values to its associated key.
V	put(K key, V value) Associates the specified value with the specified key in this map (optional operation).
void	putAll(Map<? extends K,? extends V> map) Copies all of the mappings from the specified map to this map (optional operation).
Set<V>	values() Returns a Collection view of the values contained in this map.

Methods inherited from interface java.util.Map

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

Method Detail

put

@CanIgnoreReturnValue
V put(K key,
                            V value)

Associates the specified value with the specified key in this map (optional operation). If the map previously contained a mapping for the key, the old value is replaced by the specified value. (A map m is said to contain a mapping for a key k if and only if m.containsKey(k) would return true.)

Specified by:

put in interface Map<K,V>

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

Returns:

the previous value associated with key, or null if there was no mapping for key. (A null return can also indicate that the map previously associated null with key, if the implementation supports null values.)

Throws:

IllegalArgumentException - if the given value is already bound to a different key in this bimap. The bimap will remain unmodified in this event. To avoid this exception, call forcePut(K, V) instead.

forcePut

@CanIgnoreReturnValue
V forcePut(K key,
                                 V value)

An alternate form of put that silently removes any existing entry with the value value before proceeding with the put(K, V) operation. If the bimap previously contained the provided key-value mapping, this method has no effect.

Note that a successful call to this method could cause the size of the bimap to increase by one, stay the same, or even decrease by one.

Warning: If an existing entry with this value is removed, the key for that entry is discarded and not returned.

Parameters:

key - the key with which the specified value is to be associated

value - the value to be associated with the specified key

Returns:

the value which was previously associated with the key, which may be null, or null if there was no previous entry

putAll

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

Copies all of the mappings from the specified map to this map (optional operation). The effect of this call is equivalent to that of calling put(k, v) on this map once for each mapping from key k to value v in the specified map. The behavior of this operation is undefined if the specified map is modified while the operation is in progress.

Warning: the results of calling this method may vary depending on the iteration order of map.

Specified by:

putAll in interface Map<K,V>

Parameters:

map - mappings to be stored in this map

Throws:

IllegalArgumentException - if an attempt to put any entry fails. Note that some map entries may have been added to the bimap before the exception was thrown.

values

Set<V> values()

Returns a Collection view of the values contained in this map. The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa. If the map is modified while an iteration over the collection is in progress (except through the iterator's own remove operation), the results of the iteration are undefined. The collection 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.

Because a bimap has unique values, this method returns a Set, instead of the Collection specified in the Map interface.

Specified by:

values in interface Map<K,V>

Returns:

a collection view of the values contained in this map

inverse

BiMap<V,K> inverse()

Returns the inverse view of this bimap, which maps each of this bimap's values to its associated key. The two bimaps are backed by the same data; any changes to one will appear in the other.

Note:There is no guaranteed correspondence between the iteration order of a bimap and that of its inverse.

Returns:

the inverse view of this bimap