Package org.apache.commons.collections4.multimap

Class UnmodifiableMultiValuedMap<K,V>

java.lang.Object
org.apache.commons.collections4.multimap.AbstractMultiValuedMapDecorator<K,V>
org.apache.commons.collections4.multimap.UnmodifiableMultiValuedMap<K,V>
Type Parameters:
K - the type of key elements
V - the type of value elements
All Implemented Interfaces:
Serializable, MultiValuedMap<K,V>, Unmodifiable
public final class UnmodifiableMultiValuedMap<K,V> extends AbstractMultiValuedMapDecorator<K,V> implements Unmodifiable
Decorates another MultiValuedMap to ensure it can't be altered.

Attempts to modify it will result in an UnsupportedOperationException.

Since:
4.1
See Also:

  • Method Details

    • unmodifiableMultiValuedMap

      public static <K, V> UnmodifiableMultiValuedMap<K,V> unmodifiableMultiValuedMap(MultiValuedMap<? extends K,? extends V> map)
      Factory method to create an unmodifiable MultiValuedMap.

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

      Type Parameters:
      K - the type of key elements
      V - the type of value elements
      Parameters:
      map - the map to decorate, may not be null
      Returns:
      an unmodifiable MultiValuedMap
      Throws:
      NullPointerException - if map is null

    • asMap

      public Map<K,Collection<V>> asMap()
      Description copied from interface: MultiValuedMap
      Returns a view of this multivalued map as a Map from each distinct key to the non-empty collection of that key's associated values.

      Note that this.asMap().get(k) is equivalent to this.get(k) only when k is a key contained in the multivalued map; otherwise it returns null as opposed to an empty collection.

      Changes to the returned map or the collections that serve as its values will update the underlying multivalued map, and vice versa. The map does not support put or putAll, nor do its entries support setValue.

      Specified by:
      asMap in interface MultiValuedMap<K,V>
      Overrides:
      asMap in class AbstractMultiValuedMapDecorator<K,V>
      Returns:
      a map view of the mappings in this multivalued map

    • clear

      public void clear()
      Description copied from interface: MultiValuedMap
      Removes all of the mappings from this map (optional operation).

      The map will be empty after this call returns.

      Specified by:
      clear in interface MultiValuedMap<K,V>
      Overrides:
      clear in class AbstractMultiValuedMapDecorator<K,V>

    • entries

      public Collection<Map.Entry<K,V>> entries()
      Description copied from interface: MultiValuedMap
      Returns a Collection view of the mappings contained in this multivalued map.

      The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa.

      Specified by:
      entries in interface MultiValuedMap<K,V>
      Overrides:
      entries in class AbstractMultiValuedMapDecorator<K,V>
      Returns:
      a set view of the mappings contained in this map

    • get

      public Collection<V> get(K key)
      Description copied from interface: MultiValuedMap
      Returns a view collection of the values associated with the specified key.

      This method will return an empty collection if MultiValuedMap.containsKey(Object) returns false. Changes to the returned collection will update the underlying MultiValuedMap and vice-versa.

      Specified by:
      get in interface MultiValuedMap<K,V>
      Overrides:
      get in class AbstractMultiValuedMapDecorator<K,V>
      Parameters:
      key - the key to retrieve
      Returns:
      the Collection of values, implementations should return an empty collection for no mapping

    • keys

      public MultiSet<K> keys()
      Description copied from interface: MultiValuedMap
      Returns a MultiSet view of the keys contained in this multivalued map.

      The MultiSet.getCount(Object) method of the returned multiset will give the same result a calling get(Object).size() for the same key.

      This multiset is backed by the map, so any changes in the map are reflected in the multiset.

      Specified by:
      keys in interface MultiValuedMap<K,V>
      Overrides:
      keys in class AbstractMultiValuedMapDecorator<K,V>
      Returns:
      a multiset view of the keys contained in this map

    • keySet

      public Set<K> keySet()
      Description copied from interface: MultiValuedMap
      Returns a Set view of the keys contained in this multivalued 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 result of the iteration is undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.

      Specified by:
      keySet in interface MultiValuedMap<K,V>
      Overrides:
      keySet in class AbstractMultiValuedMapDecorator<K,V>
      Returns:
      a set view of the keys contained in this map

    • mapIterator

      public MapIterator<K,V> mapIterator()
      Description copied from interface: MultiValuedMap
      Obtains a MapIterator over this multivalued map.

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

      Specified by:
      mapIterator in interface MultiValuedMap<K,V>
      Overrides:
      mapIterator in class AbstractMultiValuedMapDecorator<K,V>
      Returns:
      a map iterator

    • put

      public boolean put(K key, V value)
      Description copied from interface: MultiValuedMap
      Adds a key-value mapping to this multivalued map.

      Unlike a normal Map the previous value is not replaced. Instead, the new value is added to the collection stored against the key. Depending on the collection type used, duplicate key-value mappings may be allowed.

      The method will return true if the size of the multivalued map has been increased because of this operation.

      Specified by:
      put in interface MultiValuedMap<K,V>
      Overrides:
      put in class AbstractMultiValuedMapDecorator<K,V>
      Parameters:
      key - the key to store against
      value - the value to add to the collection at the key
      Returns:
      true if the map changed as a result of this put operation, or false if the map already contained the key-value mapping and the collection type does not allow duplicate values, e.g. when using a Set

    • putAll

      public boolean putAll(K key, Iterable<? extends V> values)
      Description copied from interface: MultiValuedMap
      Adds a mapping to the specified key for all values contained in the given Iterable.
      Specified by:
      putAll in interface MultiValuedMap<K,V>
      Overrides:
      putAll in class AbstractMultiValuedMapDecorator<K,V>
      Parameters:
      key - the key to store against
      values - the values to add to the collection at the key, may not be null
      Returns:
      true if the map changed as a result of this operation

    • putAll

      public boolean putAll(Map<? extends K,? extends V> map)
      Description copied from interface: MultiValuedMap
      Copies all mappings from the specified map to this multivalued 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.

      Specified by:
      putAll in interface MultiValuedMap<K,V>
      Overrides:
      putAll in class AbstractMultiValuedMapDecorator<K,V>
      Parameters:
      map - mappings to be stored in this map, may not be null
      Returns:
      true if the map changed as a result of this operation

    • putAll

      public boolean putAll(MultiValuedMap<? extends K,? extends V> map)
      Description copied from interface: MultiValuedMap
      Copies all mappings from the specified map to this multivalued 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.

      Specified by:
      putAll in interface MultiValuedMap<K,V>
      Overrides:
      putAll in class AbstractMultiValuedMapDecorator<K,V>
      Parameters:
      map - mappings to be stored in this map, may not be null
      Returns:
      true if the map changed as a result of this operation

    • remove

      public Collection<V> remove(Object key)
      Description copied from interface: MultiValuedMap
      Removes all values associated with the specified key.

      The returned collection may be modifiable, but updates will not be propagated to this multivalued map. In case no mapping was stored for the specified key, an empty, unmodifiable collection will be returned.

      Specified by:
      remove in interface MultiValuedMap<K,V>
      Overrides:
      remove in class AbstractMultiValuedMapDecorator<K,V>
      Parameters:
      key - the key to remove values from
      Returns:
      the values that were removed

    • removeMapping

      public boolean removeMapping(Object key, Object item)
      Description copied from interface: MultiValuedMap
      Removes a key-value mapping from the map.

      The item is removed from the collection mapped to the specified key. Other values attached to that key are unaffected.

      If the last value for a key is removed, implementations typically return an empty collection from a subsequent get(Object).

      Specified by:
      removeMapping in interface MultiValuedMap<K,V>
      Overrides:
      removeMapping in class AbstractMultiValuedMapDecorator<K,V>
      Parameters:
      key - the key to remove from
      item - the item to remove
      Returns:
      true if the mapping was removed, false otherwise

    • values

      public Collection<V> values()
      Description copied from interface: MultiValuedMap
      Gets a Collection view of all values contained in this multivalued map.

      Implementations typically return a collection containing the combination of values from all keys.

      Specified by:
      values in interface MultiValuedMap<K,V>
      Overrides:
      values in class AbstractMultiValuedMapDecorator<K,V>
      Returns:
      a collection view of the values contained in this multivalued map