com.uwyn.jhighlight.fastutil

インタフェース Function<K,V>

既知のサブインタフェースのリスト:

Char2ObjectFunction<V>, Char2ObjectMap<V>

既知の実装クラスのリスト:

AbstractChar2ObjectFunction, AbstractChar2ObjectMap, Char2ObjectFunctions.EmptyFunction, Char2ObjectFunctions.Singleton, Char2ObjectFunctions.SynchronizedFunction, Char2ObjectFunctions.UnmodifiableFunction, Char2ObjectOpenHashMap

public interface Function<K,V>

A function mapping keys into values.

Instances of this class represent functions: the main difference with Map is that functions do not in principle allow enumeration of their domain or range. The need for this interface lies in the existence of several highly optimized implementations of functions (e.g., minimal perfect hashes) which do not actually store their domain or range explicitly. In case the domain is known, containsKey(Object) can be used to perform membership queries.

The choice of naming all methods exactly as in Map makes it possible for all type-specific maps to extend type-specific functions (e.g., com.uwyn.jhighlight.fastutil.ints.Int2IntMap extends com.uwyn.jhighlight.fastutil.ints.Int2IntFunction). However, size() is allowed to return -1 to denote that the number of keys is not available (e.g., in the case of a string hash function).

Note that there is an com.uwyn.jhighlight.fastutil.objects.Object2ObjectFunction that can also set its default return value.

Warning: Equality of functions is not specified by contract, and it will usually be by reference, as there is no way to enumerate the keys and establish whether two functions represent the same mathematical entity.

関連項目:

Map

メソッドのサマリー

修飾子とタイプ	メソッドと説明
void	clear() Removes all associations from this function (optional operation).
boolean	containsKey(Object key) Returns true if this function contains a mapping for the specified key.
V	get(Object key) Returns the value associated by this function to the specified key.
V	put(K key, V value) Associates the specified value with the specified key in this function (optional operation).
V	remove(Object key) Removes this key and the associated value from this function if it is present (optional operation).
int	size() Returns the intended number of keys in this function, or -1 if no such number exists.

メソッドの詳細

put

V put(K key,
      V value)

Associates the specified value with the specified key in this function (optional operation).

パラメータ:

key - the key.

value - the value.

戻り値:

the old value, or null if no value was present for the given key.

関連項目:

Map.put(Object,Object)

get

V get(Object key)

Returns the value associated by this function to the specified key.

パラメータ:

key - the key.

戻り値:

the corresponding value, or null if no value was present for the given key.

関連項目:

Map.get(Object)

containsKey

boolean containsKey(Object key)

Returns true if this function contains a mapping for the specified key.

Note that for some kind of functions (e.g., hashes) this method will always return true.

パラメータ:

key - the key.

戻り値:

true if this function associates a value to key.

関連項目:

Map.containsKey(Object)

remove

V remove(Object key)

Removes this key and the associated value from this function if it is present (optional operation).

パラメータ:

key -

戻り値:

the old value, or null if no value was present for the given key.

関連項目:

Map.remove(Object)

size

int size()

Returns the intended number of keys in this function, or -1 if no such number exists.

Most function implementations will have some knowledge of the intended number of keys in their domain. In some cases, however, this might not be possible.

戻り値:

the intended number of keys in this function, or -1 if that number is not available.

clear

void clear()

Removes all associations from this function (optional operation).

関連項目:

Map.clear()