Interface Function<T,R>
 Type Parameters:

T
 the type of the input to the function 
R
 the type of the result of the function
 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>
Represents a function that accepts one argument and produces a result.
This is a functional interface whose functional method is apply(Object)
.
 Since:
 1.8
Method Summary
Modifier and Type  Method  Description 

default <V> Function<T,V>  andThen(Function<? super R,? extends V> after)  Returns a composed function that first applies this function to its input, and then applies the 
R  apply(T t)  Applies this function to the given argument. 
default <V> Function<V,R>  compose(Function<? super V,? extends T> before)  Returns a composed function that first applies the 
static <T> Function<T,T>  identity()  Returns a function that always returns its input argument. 
Method Detail
apply
R apply(T t)
Applies this function to the given argument.
 Parameters:

t
 the function argument  Returns:
 the function result
compose
default <V> Function<V,R> compose(Function<? super V,? extends T> before)
Returns a composed function that first applies the before
function to its input, and then applies this function to the result. If evaluation of either function throws an exception, it is relayed to the caller of the composed function.
 Type Parameters:

V
 the type of input to thebefore
function, and to the composed function  Parameters:

before
 the function to apply before this function is applied  Returns:
 a composed function that first applies the
before
function and then applies this function  Throws:

NullPointerException
 if before is null  See Also:
andThen(Function)
andThen
default <V> Function<T,V> andThen(Function<? super R,? extends V> after)
Returns a composed function that first applies this function to its input, and then applies the after
function to the result. If evaluation of either function throws an exception, it is relayed to the caller of the composed function.
 Type Parameters:

V
 the type of output of theafter
function, and of the composed function  Parameters:

after
 the function to apply after this function is applied  Returns:
 a composed function that first applies this function and then applies the
after
function  Throws:

NullPointerException
 if after is null  See Also:
compose(Function)
identity
static <T> Function<T,T> identity()
Returns a function that always returns its input argument.
 Type Parameters:

T
 the type of the input and output objects to the function  Returns:
 a function that always returns its input argument