Package org.apache.commons.collections4.bidimap

Class UnmodifiableBidiMap<K,​V>

  • Type Parameters:
    K - the type of the keys in this map
    V - the type of the values in this map
    All Implemented Interfaces:
    Map<K,​V>, BidiMap<K,​V>, Get<K,​V>, IterableGet<K,​V>, IterableMap<K,​V>, Put<K,​V>, Unmodifiable
    public final class UnmodifiableBidiMap<K,​V>
extends AbstractBidiMapDecorator<K,​V>
implements Unmodifiable
    Decorates another BidiMap to ensure it can't be altered.

    Attempts to modify it will result in an UnsupportedOperationException.

    Since:
    3.0

    • Method Detail

      • unmodifiableBidiMap

        public static <K,​V> BidiMap<K,​V> unmodifiableBidiMap​(BidiMap<? extends K,​? extends V> map)
        Factory method to create an unmodifiable map.

        If the map passed in is already unmodifiable, it is returned.

        Type Parameters:
        K - the key type
        V - the value type
        Parameters:
        map - the map to decorate, must not be null
        Returns:
        an unmodifiable BidiMap
        Throws:
        NullPointerException - if map is null
        Since:
        4.0

      • put

        public V put​(K key,
             V value)
        Description copied from interface: Put
        Note that the return type is Object, rather than V as in the Map interface. See the class Javadoc for further info.
        Specified by:
        put in interface BidiMap<K,​V>
        Specified by:
        put in interface Map<K,​V>
        Specified by:
        put in interface Put<K,​V>
        Overrides:
        put in class AbstractMapDecorator<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.)
        See Also:
        Map.put(Object, Object)

      • remove

        public V remove​(Object key)
        Specified by:
        remove in interface Get<K,​V>
        Specified by:
        remove in interface Map<K,​V>
        Overrides:
        remove in class AbstractMapDecorator<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:
        Map.remove(Object)

      • values

        public Set<V> values()
        Description copied from interface: BidiMap
        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.
        Specified by:
        values in interface BidiMap<K,​V>
        Specified by:
        values in interface Get<K,​V>
        Specified by:
        values in interface Map<K,​V>
        Overrides:
        values in class AbstractBidiMapDecorator<K,​V>
        Returns:
        a collection view of the values contained in this map
        See Also:
        Map.values()

      • 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>
        Overrides:
        removeValue in class AbstractBidiMapDecorator<K,​V>
        Parameters:
        value - the value to find the key-value pair for
        Returns:
        the key that was removed, null if nothing removed

      • mapIterator

        public MapIterator<K,​V> mapIterator()
        Description copied from class: AbstractIterableMap
        Obtains a MapIterator over the map.

        A map iterator is an efficient way of iterating over maps. There is no need to access the entry set or use Map Entry objects. 

         IterableMap<String,Integer> map = new HashedMap<String,Integer>();
 MapIterator<String,Integer> it = map.mapIterator();
 while (it.hasNext()) {
   String key = it.next();
   Integer value = it.getValue();
   it.setValue(value + 1);
 }
        Specified by:
        mapIterator in interface IterableGet<K,​V>
        Overrides:
        mapIterator in class AbstractBidiMapDecorator<K,​V>
        Returns:
        a map iterator

      • 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>
        Overrides:
        inverseBidiMap in class AbstractBidiMapDecorator<K,​V>
        Returns:
        an inverted bidirectional map