Package it.unimi.dsi.fastutil.objects

Interface Object2ReferenceFunction<K,​V>

All Superinterfaces:
Function<K,​V>, java.util.function.Function<K,​V>
Functional Interface:
This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
@FunctionalInterface
public interface Object2ReferenceFunction<K,​V>
extends Function<K,​V>
A type-specific Function; provides some additional methods that use polymorphism to avoid (un)boxing.

Type-specific versions of get(), put() and remove() cannot rely on null to denote absence of a key. Rather, they return a default return value, which is set to 0/false at creation, but can be changed using the defaultReturnValue() method.

For uniformity reasons, even functions returning objects implement the default return value (of course, in this case the default return value is initialized to null).

The default implementation of optional operations just throw an UnsupportedOperationException, except for the type-specific containsKey(), which return true. Generic versions of accessors delegate to the corresponding type-specific counterparts following the interface rules.

Warning: to fall in line as much as possible with the standard map interface, it is required that standard versions of get(), put() and remove() for maps with primitive-type keys or values return null to denote missing keys rather than wrap the default return value in an object. In case both keys and values are reference types, the default return value must be returned instead, thus violating the standard map interface when the default return value is not null.

See Also:
Function

  • Method Details

    • put

      default V put​(K key, V value)
      Adds a pair to the map (optional operation).
      Specified by:
      put in interface Function<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)

    • get

      V get​(java.lang.Object key)
      Returns the value to which the given key is mapped.
      Specified by:
      get in interface Function<K,​V>
      Parameters:
      key - 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)

    • getOrDefault

      default V getOrDefault​(java.lang.Object key, V defaultValue)
      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>
      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.
      Since:
      8.5.0
      See Also:
      Function.getOrDefault(Object, Object)

    • remove

      default V remove​(java.lang.Object key)
      Removes the mapping with the given key (optional operation).
      Specified by:
      remove in interface Function<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)

    • defaultReturnValue

      default 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 0/false/null by default.
      Parameters:
      rv - the new default return value.
      See Also:
      defaultReturnValue()

    • defaultReturnValue

      default V defaultReturnValue()
      Gets the default return value.

      This default implementation just return the default null value of the type (null for objects, 0 for scalars, false for Booleans).

      Returns:
      the current default return value.

    • andThenByte

      default Object2ByteFunction<K> andThenByte​(it.unimi.dsi.fastutil.objects.Reference2ByteFunction<V> after)

    • composeByte

      default it.unimi.dsi.fastutil.bytes.Byte2ReferenceFunction<V> composeByte​(Byte2ObjectFunction<K> before)

    • andThenShort

      default Object2ShortFunction<K> andThenShort​(it.unimi.dsi.fastutil.objects.Reference2ShortFunction<V> after)

    • composeShort

      default it.unimi.dsi.fastutil.shorts.Short2ReferenceFunction<V> composeShort​(Short2ObjectFunction<K> before)

    • andThenInt

      default Object2IntFunction<K> andThenInt​(Reference2IntFunction<V> after)

    • composeInt

      default Int2ReferenceFunction<V> composeInt​(Int2ObjectFunction<K> before)

    • andThenLong

      default Object2LongFunction<K> andThenLong​(Reference2LongFunction<V> after)

    • composeLong

      default Long2ReferenceFunction<V> composeLong​(Long2ObjectFunction<K> before)

    • andThenChar

      default Object2CharFunction<K> andThenChar​(it.unimi.dsi.fastutil.objects.Reference2CharFunction<V> after)

    • composeChar

      default it.unimi.dsi.fastutil.chars.Char2ReferenceFunction<V> composeChar​(Char2ObjectFunction<K> before)

    • andThenFloat

      default Object2FloatFunction<K> andThenFloat​(it.unimi.dsi.fastutil.objects.Reference2FloatFunction<V> after)

    • composeFloat

      default it.unimi.dsi.fastutil.floats.Float2ReferenceFunction<V> composeFloat​(Float2ObjectFunction<K> before)

    • andThenDouble

      default Object2DoubleFunction<K> andThenDouble​(Reference2DoubleFunction<V> after)

    • composeDouble

      default Double2ReferenceFunction<V> composeDouble​(Double2ObjectFunction<K> before)

    • andThenObject

      default <T> Object2ObjectFunction<K,​T> andThenObject​(Reference2ObjectFunction<? super V,​? extends T> after)

    • composeObject

      default <T> Object2ReferenceFunction<T,​V> composeObject​(Object2ObjectFunction<? super T,​? extends K> before)

    • andThenReference

      default <T> Object2ReferenceFunction<K,​T> andThenReference​(it.unimi.dsi.fastutil.objects.Reference2ReferenceFunction<? super V,​? extends T> after)

    • composeReference

      default <T> it.unimi.dsi.fastutil.objects.Reference2ReferenceFunction<T,​V> composeReference​(Reference2ObjectFunction<? super T,​? extends K> before)