Package org.apache.commons.collections4.multimap

Class AbstractMultiValuedMapDecorator<K,​V>

  • Type Parameters:
    K - the type of key elements
    V - the type of value elements
    All Implemented Interfaces:
    Serializable, MultiValuedMap<K,​V>
    Direct Known Subclasses:
    TransformedMultiValuedMap, UnmodifiableMultiValuedMap
    public abstract class AbstractMultiValuedMapDecorator<K,​V>
extends Object
implements MultiValuedMap<K,​V>, Serializable
    Decorates another MultiValuedMap to provide additional behaviour.

    Each method call made on this MultiValuedMap is forwarded to the decorated MultiValuedMap. This class is used as a framework to build to extensions such as synchronized and unmodifiable behaviour.

    Since:
    4.1
    See Also:
    Serialized Form

    • Constructor Detail

      • AbstractMultiValuedMapDecorator

        protected AbstractMultiValuedMapDecorator​(MultiValuedMap<K,​V> map)
        Constructor that wraps (not copies).
        Parameters:
        map - the map to decorate, must not be null
        Throws:
        NullPointerException - if the map is null

    • Method Detail

      • decorated

        protected MultiValuedMap<K,​V> decorated()
        The decorated multi-valued map.
        Returns:
        the map to decorate

      • size

        public int size()
        Description copied from interface: MultiValuedMap
        Gets the total size of the map.

        Implementations would return the total size of the map which is the count of the values from all keys.

        Specified by:
        size in interface MultiValuedMap<K,​V>
        Returns:
        the total size of the map

      • isEmpty

        public boolean isEmpty()
        Description copied from interface: MultiValuedMap
        Returns true if this map contains no key-value mappings.
        Specified by:
        isEmpty in interface MultiValuedMap<K,​V>
        Returns:
        true if this map contains no key-value mappings

      • containsKey

        public boolean containsKey​(Object key)
        Description copied from interface: MultiValuedMap
        Returns true if this map contains a mapping for the specified key. More formally, returns true if and only if this map contains a mapping for a key k such that (key==null ? k==null : key.equals(k)). (There can be at most one such mapping.)
        Specified by:
        containsKey in interface MultiValuedMap<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

      • containsValue

        public boolean containsValue​(Object value)
        Description copied from interface: MultiValuedMap
        Checks whether the map contains at least one mapping for the specified value.
        Specified by:
        containsValue in interface MultiValuedMap<K,​V>
        Parameters:
        value - the value to search for
        Returns:
        true if the map contains the value

      • containsMapping

        public boolean containsMapping​(Object key,
                               Object value)
        Description copied from interface: MultiValuedMap
        Checks whether the map contains a mapping for the specified key and value.
        Specified by:
        containsMapping in interface MultiValuedMap<K,​V>
        Parameters:
        key - the key to search for
        value - the value to search for
        Returns:
        true if the map contains the value

      • 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>
        Parameters:
        key - the key to retrieve
        Returns:
        the Collection of values, implementations should return an empty collection for no mapping

      • 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 multi-valued 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>
        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>
        Parameters:
        key - the key to remove from
        item - the item to remove
        Returns:
        true if the mapping was removed, false otherwise

      • 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>

      • put

        public boolean put​(K key,
                   V value)
        Description copied from interface: MultiValuedMap
        Adds a key-value mapping to this multi-valued 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 multi-valued map has been increased because of this operation.

        Specified by:
        put in interface MultiValuedMap<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

      • keySet

        public Set<K> keySet()
        Description copied from interface: MultiValuedMap
        Returns a Set view of the keys contained in this multi-valued 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>
        Returns:
        a set view of the keys contained in this map

      • entries

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

      • keys

        public MultiSet<K> keys()
        Description copied from interface: MultiValuedMap
        Returns a MultiSet view of the keys contained in this multi-valued 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>
        Returns:
        a multiset view of the keys contained in this map

      • values

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

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

        Specified by:
        values in interface MultiValuedMap<K,​V>
        Returns:
        a collection view of the values contained in this multi-valued map

      • asMap

        public Map<K,​Collection<V>> asMap()
        Description copied from interface: MultiValuedMap
        Returns a view of this multi-valued 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 multi-valued 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 multi-valued 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>
        Returns:
        a map view of the mappings in this multi-valued map

      • 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>
        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 multi-valued 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>
        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 multi-valued 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>
        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

      • mapIterator

        public MapIterator<K,​V> mapIterator()
        Description copied from interface: MultiValuedMap
        Obtains a MapIterator over this multi-valued 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>
        Returns:
        a map iterator

      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class Object