Interface Reference2ObjectMap<K,​V>

All Superinterfaces:
Function<K,​V>, java.util.function.Function<K,​V>, java.util.Map<K,​V>, Reference2ObjectFunction<K,​V>
All Known Subinterfaces:
Reference2ObjectSortedMap<K,​V>
All Known Implementing Classes:
AbstractReference2ObjectMap, AbstractReference2ObjectSortedMap, Reference2ObjectArrayMap, Reference2ObjectLinkedOpenHashMap, Reference2ObjectMaps.EmptyMap, Reference2ObjectMaps.Singleton, Reference2ObjectMaps.SynchronizedMap, Reference2ObjectMaps.UnmodifiableMap, Reference2ObjectOpenCustomHashMap, Reference2ObjectOpenHashMap, Reference2ObjectSortedMaps.EmptySortedMap, Reference2ObjectSortedMaps.Singleton, Reference2ObjectSortedMaps.SynchronizedSortedMap, Reference2ObjectSortedMaps.UnmodifiableSortedMap

public interface Reference2ObjectMap<K,​V>
extends Reference2ObjectFunction<K,​V>, java.util.Map<K,​V>
A type-specific Map; provides some additional methods that use polymorphism to avoid (un)boxing, and handling of a default return value.

Besides extending the corresponding type-specific function, this interface strengthens Map.entrySet(), keySet() and values(). Moreover, a number of methods, such as size(), defaultReturnValue(), etc., are un-defaulted as their function default do not make sense for a map. Maps returning entry sets of type Reference2ObjectMap.FastEntrySet support also fast iteration.

This interface specifies reference equality semantics (members will be compared equal with == instead of equals) for its keys or values (or both), which may result in breaks in contract if attempted to be used with non reference-equality semantics based Maps. For example, a aReferenceToIntMap.equals(aObjectToIntMap) may return different a different result then aObjectToIntMap.equals(aReferenceToIntMap), in violation of equals's contract requiring it being symmetric.

A submap or subset may or may not have an independent default return value (which however must be initialized to the default return value of the originator).

See Also:
Map
  • Method Details

    • size

      int size()
      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>
      Returns:
      the number of key-value mappings in this map.
      See Also:
      Size64
    • clear

      default void clear()
      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>
      Throws:
      java.lang.UnsupportedOperationException - if the clear() operation is not supported by this map
      See Also:
      Map.clear()
    • defaultReturnValue

      void defaultReturnValue​(V rv)
      Sets the default return value (optional operation). This value must be returned by type-specific versions of get(), put() and remove() to denote that the map does not contain the specified key. It must be null by default.

      Warning: Changing this to a non-null value can have unforeseen consequences. Especially, it breaks compatibility with the specifications of Java's Map interface. It has to be used with great care and thorough study of all method comments is recommended.

      Specified by:
      defaultReturnValue in interface Reference2ObjectFunction<K,​V>
      Parameters:
      rv - the new default return value.
      See Also:
      defaultReturnValue()
    • defaultReturnValue

      V defaultReturnValue()
      Gets the default return value.
      Specified by:
      defaultReturnValue in interface Reference2ObjectFunction<K,​V>
      Returns:
      the current default return value.
    • reference2ObjectEntrySet

      ObjectSet<Reference2ObjectMap.Entry<K,​V>> reference2ObjectEntrySet()
      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).

      Returns:
      a type-specific set view of the mappings contained in this map.
      See Also:
      Map.entrySet()
    • entrySet

      default ObjectSet<java.util.Map.Entry<K,​V>> entrySet()
      Returns a set view of the mappings contained in this map.
      Specified by:
      entrySet in interface java.util.Map<K,​V>
      Returns:
      a set view of the mappings contained in this map.
      See Also:
      Map.entrySet()
      API Notes:
      Note that this specification strengthens the one given in Map.entrySet().
    • put

      default V put​(K key, V value)
      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 Reference2ObjectFunction<K,​V>
      Parameters:
      key - the key.
      value - 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

      default V remove​(java.lang.Object key)
      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 Reference2ObjectFunction<K,​V>
      Parameters:
      key - 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

      ReferenceSet<K> keySet()
      Specified by:
      keySet in interface java.util.Map<K,​V>
      Returns:
      a set view of the keys contained in this map.
      See Also:
      Map.keySet()
      API Notes:
      Note that this specification strengthens the one given in Map.keySet().
    • values

      ObjectCollection<V> values()
      Specified by:
      values in interface java.util.Map<K,​V>
      Returns:
      a set view of the values contained in this map.
      See Also:
      Map.values()
      API Notes:
      Note that this specification strengthens the one given in Map.values().
    • containsKey

      boolean containsKey​(java.lang.Object key)
      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>
      Parameters:
      key - the key.
      Returns:
      true if this function associates a value to key.
      See Also:
      Map.containsKey(Object)
    • forEach

      default void forEach​(java.util.function.BiConsumer<? super K,​? super V> consumer)
      Specified by:
      forEach in interface java.util.Map<K,​V>
    • getOrDefault

      default V getOrDefault​(java.lang.Object key, V defaultValue)
      Description copied from interface: Reference2ObjectFunction
      Returns the value associated by this function to the specified key, or give the specified value if not present.
      Specified by:
      getOrDefault in interface Function<K,​V>
      Specified by:
      getOrDefault in interface java.util.Map<K,​V>
      Specified by:
      getOrDefault in interface Reference2ObjectFunction<K,​V>
      Parameters:
      key - the key.
      defaultValue - the value to return if not present.
      Returns:
      the corresponding value, or defaultValue if no value was present for the given key.
      See Also:
      Function.getOrDefault(Object, Object)