Class Reference2ReferenceArrayMap<K,​V>

java.lang.Object
it.unimi.dsi.fastutil.objects.AbstractReference2ReferenceFunction<K,​V>
it.unimi.dsi.fastutil.objects.AbstractReference2ReferenceMap<K,​V>
it.unimi.dsi.fastutil.objects.Reference2ReferenceArrayMap<K,​V>
All Implemented Interfaces:
Function<K,​V>, Reference2ReferenceFunction<K,​V>, Reference2ReferenceMap<K,​V>, java.io.Serializable, java.lang.Cloneable, java.util.function.Function<K,​V>, java.util.Map<K,​V>

public class Reference2ReferenceArrayMap<K,​V>
extends AbstractReference2ReferenceMap<K,​V>
implements java.io.Serializable, java.lang.Cloneable
A simple, brute-force implementation of a map based on two parallel backing arrays.

The main purpose of this implementation is that of wrapping cleanly the brute-force approach to the storage of a very small number of pairs: just put them into two parallel arrays and scan linearly to find an item.

See Also:
Serialized Form
  • Constructor Details

    • Reference2ReferenceArrayMap

      public Reference2ReferenceArrayMap​(java.lang.Object[] key, java.lang.Object[] value)
      Creates a new empty array map with given key and value backing arrays. The resulting map will have as many entries as the given arrays.

      It is responsibility of the caller that the elements of key are distinct.

      Parameters:
      key - the key array.
      value - the value array (it must have the same length as key).
    • Reference2ReferenceArrayMap

      public Reference2ReferenceArrayMap()
      Creates a new empty array map.
    • Reference2ReferenceArrayMap

      public Reference2ReferenceArrayMap​(int capacity)
      Creates a new empty array map of given capacity.
      Parameters:
      capacity - the initial capacity.
    • Reference2ReferenceArrayMap

      public Reference2ReferenceArrayMap​(Reference2ReferenceMap<K,​V> m)
      Creates a new empty array map copying the entries of a given map.
      Parameters:
      m - a map.
    • Reference2ReferenceArrayMap

      public Reference2ReferenceArrayMap​(java.util.Map<? extends K,​? extends V> m)
      Creates a new empty array map copying the entries of a given map.
      Parameters:
      m - a map.
    • Reference2ReferenceArrayMap

      public Reference2ReferenceArrayMap​(java.lang.Object[] key, java.lang.Object[] value, int size)
      Creates a new array map with given key and value backing arrays, using the given number of elements.

      It is responsibility of the caller that the first size elements of key are distinct.

      Parameters:
      key - the key array.
      value - the value array (it must have the same length as key).
      size - the number of valid elements in key and value.
  • Method Details

    • reference2ReferenceEntrySet

      public Reference2ReferenceMap.FastEntrySet<K,​V> reference2ReferenceEntrySet()
      Description copied from interface: Reference2ReferenceMap
      Returns a type-specific set view of the mappings contained in this map.

      This method is necessary because there is no inheritance along type parameters: it is thus impossible to strengthen Map.entrySet() so that it returns an ObjectSet of type-specific entries (the latter makes it possible to access keys and values with type-specific methods).

      Specified by:
      reference2ReferenceEntrySet in interface Reference2ReferenceMap<K,​V>
      Returns:
      a type-specific set view of the mappings contained in this map.
      See Also:
      Map.entrySet()
    • get

      public V get​(java.lang.Object k)
      Description copied from interface: Reference2ReferenceFunction
      Returns the value to which the given key is mapped.
      Specified by:
      get in interface Function<K,​V>
      Specified by:
      get in interface java.util.Map<K,​V>
      Specified by:
      get in interface Reference2ReferenceFunction<K,​V>
      Parameters:
      k - the key.
      Returns:
      the corresponding value, or the default return value if no value was present for the given key.
      See Also:
      Function.get(Object)
    • size

      public int size()
      Description copied from interface: Reference2ReferenceMap
      Returns the number of key/value mappings in this map. If the map contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.
      Specified by:
      size in interface Function<K,​V>
      Specified by:
      size in interface java.util.Map<K,​V>
      Specified by:
      size in interface Reference2ReferenceMap<K,​V>
      Returns:
      the number of key-value mappings in this map.
      See Also:
      Size64
    • clear

      public void clear()
      Description copied from interface: Reference2ReferenceMap
      Removes all of the mappings from this map (optional operation). The map will be empty after this call returns.
      Specified by:
      clear in interface Function<K,​V>
      Specified by:
      clear in interface java.util.Map<K,​V>
      Specified by:
      clear in interface Reference2ReferenceMap<K,​V>
      See Also:
      Map.clear()
    • containsKey

      public boolean containsKey​(java.lang.Object k)
      Description copied from class: AbstractReference2ReferenceMap
      Returns true if this function contains a mapping for the specified key.
      Specified by:
      containsKey in interface Function<K,​V>
      Specified by:
      containsKey in interface java.util.Map<K,​V>
      Specified by:
      containsKey in interface Reference2ReferenceMap<K,​V>
      Overrides:
      containsKey in class AbstractReference2ReferenceMap<K,​V>
      Parameters:
      k - the key.
      Returns:
      true if this function associates a value to key.
      See Also:
      Map.containsKey(Object)
    • containsValue

      public boolean containsValue​(java.lang.Object v)
      Description copied from class: AbstractReference2ReferenceMap
      Specified by:
      containsValue in interface java.util.Map<K,​V>
      Overrides:
      containsValue in class AbstractReference2ReferenceMap<K,​V>
    • isEmpty

      public boolean isEmpty()
      Specified by:
      isEmpty in interface java.util.Map<K,​V>
      Overrides:
      isEmpty in class AbstractReference2ReferenceMap<K,​V>
    • put

      public V put​(K k, V v)
      Description copied from interface: Reference2ReferenceMap
      Adds a pair to the map (optional operation).

      This default implementation just delegates to the corresponding function method.

      Specified by:
      put in interface Function<K,​V>
      Specified by:
      put in interface java.util.Map<K,​V>
      Specified by:
      put in interface Reference2ReferenceFunction<K,​V>
      Specified by:
      put in interface Reference2ReferenceMap<K,​V>
      Parameters:
      k - the key.
      v - the value.
      Returns:
      the old value, or the default return value if no value was present for the given key.
      See Also:
      Function.put(Object,Object)
    • remove

      public V remove​(java.lang.Object k)
      Description copied from interface: Reference2ReferenceMap
      Removes the mapping with the given key (optional operation).

      This default implementation just delegates to the corresponding type-specific–function method.

      Specified by:
      remove in interface Function<K,​V>
      Specified by:
      remove in interface java.util.Map<K,​V>
      Specified by:
      remove in interface Reference2ReferenceFunction<K,​V>
      Specified by:
      remove in interface Reference2ReferenceMap<K,​V>
      Parameters:
      k - the key.
      Returns:
      the old value, or the default return value if no value was present for the given key.
      See Also:
      Function.remove(Object)
    • keySet

      public ReferenceSet<K> keySet()
      Description copied from class: AbstractReference2ReferenceMap
      Returns a type-specific-set view of the keys of this map.

      The view is backed by the set returned by Map.entrySet(). Note that no attempt is made at caching the result of this method, as this would require adding some attributes that lightweight implementations would not need. Subclasses may easily override this policy by calling this method and caching the result, but implementors are encouraged to write more efficient ad-hoc implementations.

      Specified by:
      keySet in interface java.util.Map<K,​V>
      Specified by:
      keySet in interface Reference2ReferenceMap<K,​V>
      Overrides:
      keySet in class AbstractReference2ReferenceMap<K,​V>
      Returns:
      a set view of the keys of this map; it may be safely cast to a type-specific interface.
      See Also:
      Map.keySet()
    • values

      public ReferenceCollection<V> values()
      Description copied from class: AbstractReference2ReferenceMap
      Returns a type-specific-set view of the values of this map.

      The view is backed by the set returned by Map.entrySet(). Note that no attempt is made at caching the result of this method, as this would require adding some attributes that lightweight implementations would not need. Subclasses may easily override this policy by calling this method and caching the result, but implementors are encouraged to write more efficient ad-hoc implementations.

      Specified by:
      values in interface java.util.Map<K,​V>
      Specified by:
      values in interface Reference2ReferenceMap<K,​V>
      Overrides:
      values in class AbstractReference2ReferenceMap<K,​V>
      Returns:
      a set view of the values of this map; it may be safely cast to a type-specific interface.
      See Also:
      Map.values()
    • clone

      public Reference2ReferenceArrayMap<K,​V> clone()
      Returns a deep copy of this map.

      This method performs a deep copy of this hash map; the data stored in the map, however, is not cloned. Note that this makes a difference only for object keys.

      Returns:
      a deep copy of this map.