compact1, compact2, compact3

java.util.function

Interface Function<T,R>

Type Parameters:

T - the type of the input to the apply operation

R - the type of the result of the apply operation

All Known Subinterfaces:

UnaryOperator<T>

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 Function<T,R>

Apply a function to the input argument, yielding an appropriate result. A function may variously provide a mapping between types, object instances or keys and values or any other form of transformation upon the input.

Since:

1.8

Method Summary

Modifier and Type	Method and Description
default <V> Function<T,V>	andThen(Function<? super R,? extends V> after) Returns a new function which applies this function followed by the provided function.
R	apply(T t) Compute the result of applying the function to the input argument
default <V> Function<V,R>	compose(Function<? super V,? extends T> before) Returns a new function which applies the provided function followed by this function.
static <T> Function<T,T>	identity() Returns a Function whose apply method returns its input.

Method Detail

apply

R apply(T t)

Compute the result of applying the function to the input argument

Parameters:

t - the input object

Returns:

the function result

compose

default <V> Function<V,R> compose(Function<? super V,? extends T> before)

Returns a new function which applies the provided function followed by this function. If either function throws an exception, it is relayed to the caller.

Type Parameters:

V - type of input objects to the combined function. May be the same type as <T> or <R>

Parameters:

before - an additional function to be applied before this function is applied

Returns:

a function which performs the provided function followed by this function

Throws:

NullPointerException - if before is null

andThen

default <V> Function<T,V> andThen(Function<? super R,? extends V> after)

Returns a new function which applies this function followed by the provided function. If either function throws an exception, it is relayed to the caller.

Type Parameters:

V - type of output objects to the combined function. May be the same type as <T> or <R>

Parameters:

after - an additional function to be applied after this function is applied

Returns:

a function which performs this function followed by the provided function

Throws:

NullPointerException - if after is null

identity

static <T> Function<T,T> identity()

Returns a Function whose apply method returns its input.

Type Parameters:

T - the type of the input and output objects to the function