Package org.apache.commons.collections4.bidimap

Class AbstractDualBidiMap<K,V>

java.lang.Object
org.apache.commons.collections4.bidimap.AbstractDualBidiMap<K,V>
Type Parameters:
K - the type of the keys in the map
V - the type of the values in the map
All Implemented Interfaces:
Map<K,V>, BidiMap<K,V>, Get<K,V>, IterableGet<K,V>, IterableMap<K,V>, Put<K,V>
Direct Known Subclasses:
DualHashBidiMap, DualLinkedHashBidiMap, DualTreeBidiMap
public abstract class AbstractDualBidiMap<K,V> extends Object implements BidiMap<K,V>
Abstract BidiMap implemented using two maps.

An implementation can be written simply by implementing the createBidiMap(Map, Map, BidiMap) method.

Since:
3.0
See Also:

  • Constructor Details

    • AbstractDualBidiMap

      protected AbstractDualBidiMap()
      Creates an empty map, initialized by createMap.

      This constructor remains in place for deserialization. All other usage is deprecated in favor of AbstractDualBidiMap(Map, Map).

    • AbstractDualBidiMap

      protected AbstractDualBidiMap(Map<K,V> normalMap, Map<V,K> reverseMap)
      Creates an empty map using the two maps specified as storage.

      The two maps must be a matching pair, normal and reverse. They will typically both be empty.

      Neither map is validated, so nulls may be passed in. If you choose to do this then the subclass constructor must populate the maps[] instance variable itself.

      Parameters:
      normalMap - the normal direction map
      reverseMap - the reverse direction map
      Since:
      3.1

    • AbstractDualBidiMap

      protected AbstractDualBidiMap(Map<K,V> normalMap, Map<V,K> reverseMap, BidiMap<V,K> inverseBidiMap)
      Constructs a map that decorates the specified maps, used by the subclass createBidiMap implementation.
      Parameters:
      normalMap - the normal direction map
      reverseMap - the reverse direction map
      inverseBidiMap - the inverse BidiMap

  • Method Details

    • clear

      public void clear()
      Description copied from interface: Put
      Removes all of the mappings from this map.
      Specified by:
      clear in interface Map<K,V>
      Specified by:
      clear in interface Put<K,V>
      See Also:

    • containsKey

      public boolean containsKey(Object key)
      Description copied from interface: Get
      Tests for presence of a given key.
      Specified by:
      containsKey in interface Get<K,V>
      Specified by:
      containsKey in interface Map<K,V>
      Parameters:
      key - key whose presence in this map is to be tested
      Returns:
      true if this map contains a mapping for the specified key
      See Also:

    • containsValue

      public boolean containsValue(Object value)
      Description copied from interface: Get
      Tests for presence of a given value.
      Specified by:
      containsValue in interface Get<K,V>
      Specified by:
      containsValue in interface Map<K,V>
      Parameters:
      value - value whose presence in this map is to be tested
      Returns:
      true if this map maps one or more keys to the specified value
      See Also:

    • createBidiMap

      protected abstract BidiMap<V,K> createBidiMap(Map<V,K> normalMap, Map<K,V> reverseMap, BidiMap<K,V> inverseMap)
      Creates a new instance of the subclass.
      Parameters:
      normalMap - the normal direction map
      reverseMap - the reverse direction map
      inverseMap - this map, which is the inverse in the new map
      Returns:
      the bidi map

    • createEntrySetIterator

      protected Iterator<Map.Entry<K,V>> createEntrySetIterator(Iterator<Map.Entry<K,V>> iterator)
      Creates an entry set iterator. Subclasses can override this to return iterators with different properties.
      Parameters:
      iterator - the iterator to decorate
      Returns:
      the entrySet iterator

    • createKeySetIterator

      protected Iterator<K> createKeySetIterator(Iterator<K> iterator)
      Creates a key set iterator. Subclasses can override this to return iterators with different properties.
      Parameters:
      iterator - the iterator to decorate
      Returns:
      the keySet iterator

    • createValuesIterator

      protected Iterator<V> createValuesIterator(Iterator<V> iterator)
      Creates a values iterator. Subclasses can override this to return iterators with different properties.
      Parameters:
      iterator - the iterator to decorate
      Returns:
      the values iterator

    • entrySet

      public Set<Map.Entry<K,V>> entrySet()
      Gets an entrySet view of the map. Changes made on the set are reflected in the map. The set supports remove and clear but not add.

      The Map Entry setValue() method only allow a new value to be set. If the value being set is already in the map, an IllegalArgumentException is thrown (as setValue cannot change the size of the map).

      Specified by:
      entrySet in interface Get<K,V>
      Specified by:
      entrySet in interface Map<K,V>
      Returns:
      the entrySet view
      See Also:

    • equals

      public boolean equals(Object obj)
      Specified by:
      equals in interface Map<K,V>
      Overrides:
      equals in class Object

    • get

      public V get(Object key)
      Description copied from interface: Get
      Gets a value at a given key.
      Specified by:
      get in interface Get<K,V>
      Specified by:
      get in interface Map<K,V>
      Parameters:
      key - the key whose associated value is to be returned
      Returns:
      the value to which the specified key is mapped, or null if this map contains no mapping for the key
      See Also:

    • getKey

      public K getKey(Object value)
      Description copied from interface: BidiMap
      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).

      Specified by:
      getKey in interface BidiMap<K,V>
      Parameters:
      value - the value to find the key for
      Returns:
      the mapped key, or null if not found

    • hashCode

      public int hashCode()
      Specified by:
      hashCode in interface Map<K,V>
      Overrides:
      hashCode in class Object

    • inverseBidiMap

      public BidiMap<V,K> inverseBidiMap()
      Description copied from interface: BidiMap
      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.

      Specified by:
      inverseBidiMap in interface BidiMap<K,V>
      Returns:
      an inverted bidirectional map

    • isEmpty

      public boolean isEmpty()
      Description copied from interface: Get
      Tests whether this instance contains any key-value mappings.
      Specified by:
      isEmpty in interface Get<K,V>
      Specified by:
      isEmpty in interface Map<K,V>
      Returns:
      true if this map contains no key-value mappings
      See Also:

    • keySet

      public Set<K> keySet()
      Gets a keySet view of the map. Changes made on the view are reflected in the map. The set supports remove and clear but not add.
      Specified by:
      keySet in interface Get<K,V>
      Specified by:
      keySet in interface Map<K,V>
      Returns:
      the keySet view
      See Also:

    • mapIterator

      public MapIterator<K,V> mapIterator()
      Obtains a MapIterator over the map. The iterator implements AbstractDualBidiMap.BidiMapIterator. This implementation relies on the entrySet iterator.
      Specified by:
      mapIterator in interface IterableGet<K,V>
      Returns:
      a map iterator

    • put

      public V put(K key, V value)
      Description copied from interface: BidiMap
      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
      Specified by:
      put in interface BidiMap<K,V>
      Specified by:
      put in interface Map<K,V>
      Specified by:
      put in interface Put<K,V>
      Parameters:
      key - the key to store
      value - the value to store
      Returns:
      the previous value mapped to this key
      See Also:

    • putAll

      public void putAll(Map<? extends K,? extends V> map)
      Description copied from interface: Put
      Copies all of the mappings from the specified map to this map.
      Specified by:
      putAll in interface Map<K,V>
      Specified by:
      putAll in interface Put<K,V>
      Parameters:
      map - mappings to be stored in this map
      See Also:

    • remove

      public V remove(Object key)
      Description copied from interface: Get
      Remove a key-value mappings.
      Specified by:
      remove in interface Get<K,V>
      Specified by:
      remove in interface Map<K,V>
      Parameters:
      key - key whose mapping is to be removed from the map
      Returns:
      the previous value associated with key, or null if there was no mapping for key.
      See Also:

    • removeValue

      public K removeValue(Object value)
      Description copied from interface: BidiMap
      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).

      Specified by:
      removeValue in interface BidiMap<K,V>
      Parameters:
      value - the value to find the key-value pair for
      Returns:
      the key that was removed, null if nothing removed

    • size

      public int size()
      Description copied from interface: Get
      Gets the number of key-value mappings in this map.
      Specified by:
      size in interface Get<K,V>
      Specified by:
      size in interface Map<K,V>
      Returns:
      the number of key-value mappings in this map.
      See Also:

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • values

      public Set<V> values()
      Gets a values view of the map. Changes made on the view are reflected in the map. The set supports remove and clear but not add.
      Specified by:
      values in interface BidiMap<K,V>
      Specified by:
      values in interface Get<K,V>
      Specified by:
      values in interface Map<K,V>
      Returns:
      the values view
      See Also: