Type Parameters:

T1 - argument 1 of the function

T2 - argument 2 of the function

T3 - argument 3 of the function

T4 - argument 4 of the function

R - return type of the function

All Superinterfaces:

java.io.Serializable

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 Function4<T1,T2,T3,T4,R>
extends java.io.Serializable
```
Represents a function with 4 arguments.

Field Summary

Fields
Modifier and Type Field Description

static long serialVersionUID
The serial version UID for serialization.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method	Description
`default <V> Function4<T1,T2,T3,T4,V>`	`andThen(@NonNull java.util.function.Function<? super R,? extends V> after)`	Returns a composed function that first applies this Function4 to the given argument and then applies Function `after` to the result.
`default Function3<T2,T3,T4,R>`	`apply(T1 t1)`	Applies this function partially to one argument.
`default Function2<T3,T4,R>`	`apply(T1 t1, T2 t2)`	Applies this function partially to two arguments.
`default Function1<T4,R>`	`apply(T1 t1, T2 t2, T3 t3)`	Applies this function partially to three arguments.
`R`	`apply(T1 t1, T2 t2, T3 t3, T4 t4)`	Applies this function to 4 arguments and returns the result.
`default int`	`arity()`	Returns the number of function arguments.
`default <S> Function4<S,T2,T3,T4,R>`	`compose1(@NonNull Function1<? super S,? extends T1> before)`	Returns a composed function that first applies the Function `before` to the 1st argument and then applies this Function4 to the result and the other arguments.
`default <S> Function4<T1,S,T3,T4,R>`	`compose2(@NonNull Function1<? super S,? extends T2> before)`	Returns a composed function that first applies the Function `before` to the 2nd argument and then applies this Function4 to the result and the other arguments.
`default <S> Function4<T1,T2,S,T4,R>`	`compose3(@NonNull Function1<? super S,? extends T3> before)`	Returns a composed function that first applies the Function `before` to the 3rd argument and then applies this Function4 to the result and the other arguments.
`default <S> Function4<T1,T2,T3,S,R>`	`compose4(@NonNull Function1<? super S,? extends T4> before)`	Returns a composed function that first applies the Function `before` to the 4th argument and then applies this Function4 to the result and the other arguments.
`static <T1,T2,T3,T4,R> Function4<T1,T2,T3,T4,R>`	`constant(R value)`	Returns a function that always returns the constant value that you give in parameter.
`default Function1<T1,Function1<T2,Function1<T3,Function1<T4,R>>>>`	`curried()`	Returns a curried version of this function.
`default boolean`	`isMemoized()`	Checks if this function is memoizing (= caching) computed values.
`static <T1,T2,T3,T4,R> Function4<T1,T2,T3,T4,Option<R>>`	`lift(@NonNull Function4<? super T1,? super T2,? super T3,? super T4,? extends R> partialFunction)`	Lifts the given `partialFunction` into a total function that returns an `Option` result.
`static <T1,T2,T3,T4,R> Function4<T1,T2,T3,T4,Try<R>>`	`liftTry(@NonNull Function4<? super T1,? super T2,? super T3,? super T4,? extends R> partialFunction)`	Lifts the given `partialFunction` into a total function that returns an `Try` result.
`default Function4<T1,T2,T3,T4,R>`	`memoized()`	Returns a memoizing version of this function, which computes the return value for given arguments only one time.
`static <T1,T2,T3,T4,R> Function4<T1,T2,T3,T4,R>`	`narrow(Function4<? super T1,? super T2,? super T3,? super T4,? extends R> f)`	Narrows the given `Function4<? super T1, ? super T2, ? super T3, ? super T4, ? extends R>` to `Function4<T1, T2, T3, T4, R>`
`static <T1,T2,T3,T4,R> Function4<T1,T2,T3,T4,R>`	`of(@NonNull Function4<T1,T2,T3,T4,R> methodReference)`	Creates a `Function4` based on method reference lambda expression Examples (w.l.o.g.
`default Function4<T4,T3,T2,T1,R>`	`reversed()`	Returns a reversed version of this function.
`default Function1<Tuple4<T1,T2,T3,T4>,R>`	`tupled()`	Returns a tupled version of this function.

- Field Detail
  - serialVersionUID
```
static final long serialVersionUID
```
    The serial version UID for serialization.
    
    See Also:
    
    Constant Field Values
- Method Detail
  - constant
```
static <T1,T2,T3,T4,R> Function4<T1,T2,T3,T4,R> constant(R value)
```
    Returns a function that always returns the constant value that you give in parameter.
    
    Type Parameters:
    
    T1 - generic parameter type 1 of the resulting function
    
    T2 - generic parameter type 2 of the resulting function
    
    T3 - generic parameter type 3 of the resulting function
    
    T4 - generic parameter type 4 of the resulting function
    
    R - the result type
    
    Parameters:
    
    value - the value to be returned
    
    Returns:
    
    a function always returning the given value
  - of
```
static <T1,T2,T3,T4,R> Function4<T1,T2,T3,T4,R> of(@NonNull Function4<T1,T2,T3,T4,R> methodReference)
```
    Creates a Function4 based on
    
    method reference
    
    lambda expression
    
    Examples (w.l.o.g. referring to Function1):
    // using a lambda expression Function1<Integer, Integer> add1 = Function1.of(i -> i + 1); // using a method reference (, e.g. Integer method(Integer i) { return i + 1; }) Function1<Integer, Integer> add2 = Function1.of(this::method); // using a lambda reference Function1<Integer, Integer> add3 = Function1.of(add1::apply);
    
    Caution: Reflection loses type information of lambda references.
    // type of a lambda expression Type<?, ?> type1 = add1.getType(); // (Integer) -> Integer // type of a method reference Type<?, ?> type2 = add2.getType(); // (Integer) -> Integer // type of a lambda reference Type<?, ?> type3 = add3.getType(); // (Object) -> Object
    Type Parameters:
    
    R - return type
    
    T1 - 1st argument
    
    T2 - 2nd argument
    
    T3 - 3rd argument
    
    T4 - 4th argument
    
    Parameters:
    
    methodReference - (typically) a method reference, e.g. Type::method
    
    Returns:
    
    a Function4
  - lift
```
static <T1,T2,T3,T4,R> Function4<T1,T2,T3,T4,Option<R>> lift(@NonNull Function4<? super T1,? super T2,? super T3,? super T4,? extends R> partialFunction)
```
    Lifts the given partialFunction into a total function that returns an Option result.
    
    Type Parameters:
    
    R - return type
    
    T1 - 1st argument
    
    T2 - 2nd argument
    
    T3 - 3rd argument
    
    T4 - 4th argument
    
    Parameters:
    
    partialFunction - a function that is not defined for all values of the domain (e.g. by throwing)
    
    Returns:
    
    a function that applies arguments to the given partialFunction and returns Some(result) if the function is defined for the given arguments, and None otherwise.
  - liftTry
```
static <T1,T2,T3,T4,R> Function4<T1,T2,T3,T4,Try<R>> liftTry(@NonNull Function4<? super T1,? super T2,? super T3,? super T4,? extends R> partialFunction)
```
    Lifts the given partialFunction into a total function that returns an Try result.
    
    Type Parameters:
    
    R - return type
    
    T1 - 1st argument
    
    T2 - 2nd argument
    
    T3 - 3rd argument
    
    T4 - 4th argument
    
    Parameters:
    
    partialFunction - a function that is not defined for all values of the domain (e.g. by throwing)
    
    Returns:
    
    a function that applies arguments to the given partialFunction and returns Success(result) if the function is defined for the given arguments, and Failure(throwable) otherwise.
  - narrow
```
static <T1,T2,T3,T4,R> Function4<T1,T2,T3,T4,R> narrow(Function4<? super T1,? super T2,? super T3,? super T4,? extends R> f)
```
    Narrows the given Function4<? super T1, ? super T2, ? super T3, ? super T4, ? extends R> to Function4<T1, T2, T3, T4, R>
    
    Type Parameters:
    
    R - return type
    
    T1 - 1st argument
    
    T2 - 2nd argument
    
    T3 - 3rd argument
    
    T4 - 4th argument
    
    Parameters:
    
    f - A Function4
    
    Returns:
    
    the given f instance as narrowed type Function4<T1, T2, T3, T4, R>
  - apply
```
R apply(T1 t1,
        T2 t2,
        T3 t3,
        T4 t4)
```
    Applies this function to 4 arguments and returns the result.
    
    Parameters:
    
    t1 - argument 1
    
    t2 - argument 2
    
    t3 - argument 3
    
    t4 - argument 4
    
    Returns:
    
    the result of function application
  - apply
```
default Function3<T2,T3,T4,R> apply(T1 t1)
```
    Applies this function partially to one argument.
    
    Parameters:
    
    t1 - argument 1
    
    Returns:
    
    a partial application of this function
  - apply
```
default Function2<T3,T4,R> apply(T1 t1,
                                             T2 t2)
```
    Applies this function partially to two arguments.
    
    Parameters:
    
    t1 - argument 1
    
    t2 - argument 2
    
    Returns:
    
    a partial application of this function
  - apply
```
default Function1<T4,R> apply(T1 t1,
                                    T2 t2,
                                    T3 t3)
```
    Applies this function partially to three arguments.
    
    Parameters:
    
    t1 - argument 1
    
    t2 - argument 2
    
    t3 - argument 3
    
    Returns:
    
    a partial application of this function
  - arity
```
default int arity()
```
    Returns the number of function arguments.
    
    Returns:
    
    an int value >= 0
    
    See Also:
    
    Arity
  - curried
```
default Function1<T1,Function1<T2,Function1<T3,Function1<T4,R>>>> curried()
```
    Returns a curried version of this function.
    
    Returns:
    
    a curried function equivalent to this.
  - tupled
```
default Function1<Tuple4<T1,T2,T3,T4>,R> tupled()
```
    Returns a tupled version of this function.
    
    Returns:
    
    a tupled function equivalent to this.
  - reversed
```
default Function4<T4,T3,T2,T1,R> reversed()
```
    Returns a reversed version of this function. This may be useful in a recursive context.
    
    Returns:
    
    a reversed function equivalent to this.
  - memoized
```
default Function4<T1,T2,T3,T4,R> memoized()
```
    Returns a memoizing version of this function, which computes the return value for given arguments only one time. On subsequent calls given the same arguments the memoized value is returned.
    Please note that memoizing functions do not permit null as single argument or return value.
    
    Returns:
    
    a memoizing function equivalent to this.
  - isMemoized
```
default boolean isMemoized()
```
    Checks if this function is memoizing (= caching) computed values.
    
    Returns:
    
    true, if this function is memoizing, false otherwise
  - andThen
```
default <V> Function4<T1,T2,T3,T4,V> andThen(@NonNull java.util.function.Function<? super R,? extends V> after)
```
    Returns a composed function that first applies this Function4 to the given argument and then applies Function after to the result.
    
    Type Parameters:
    
    V - return type of after
    
    Parameters:
    
    after - the function applied after this
    
    Returns:
    
    a function composed of this and after
    
    Throws:
    
    java.lang.NullPointerException - if after is null
  - compose1
```
default <S> Function4<S,T2,T3,T4,R> compose1(@NonNull Function1<? super S,? extends T1> before)
```
    Returns a composed function that first applies the Function before to the 1st argument and then applies this Function4 to the result and the other arguments.
    
    Type Parameters:
    
    S - argument type of before
    
    Parameters:
    
    before - the function applied before this
    
    Returns:
    
    a function composed of before and this
    
    Throws:
    
    java.lang.NullPointerException - if before is null
  - compose2
```
default <S> Function4<T1,S,T3,T4,R> compose2(@NonNull Function1<? super S,? extends T2> before)
```
    Returns a composed function that first applies the Function before to the 2nd argument and then applies this Function4 to the result and the other arguments.
    
    Type Parameters:
    
    S - argument type of before
    
    Parameters:
    
    before - the function applied before this
    
    Returns:
    
    a function composed of before and this
    
    Throws:
    
    java.lang.NullPointerException - if before is null
  - compose3
```
default <S> Function4<T1,T2,S,T4,R> compose3(@NonNull Function1<? super S,? extends T3> before)
```
    Returns a composed function that first applies the Function before to the 3rd argument and then applies this Function4 to the result and the other arguments.
    
    Type Parameters:
    
    S - argument type of before
    
    Parameters:
    
    before - the function applied before this
    
    Returns:
    
    a function composed of before and this
    
    Throws:
    
    java.lang.NullPointerException - if before is null
  - compose4
```
default <S> Function4<T1,T2,T3,S,R> compose4(@NonNull Function1<? super S,? extends T4> before)
```
    Returns a composed function that first applies the Function before to the 4th argument and then applies this Function4 to the result and the other arguments.
    
    Type Parameters:
    
    S - argument type of before
    
    Parameters:
    
    before - the function applied before this
    
    Returns:
    
    a function composed of before and this
    
    Throws:
    
    java.lang.NullPointerException - if before is null

Interface Function4<T1,​T2,​T3,​T4,​R>

Field Summary

Method Summary

Field Detail

serialVersionUID

Method Detail

constant

of

lift

liftTry

narrow

apply

apply

apply

apply

arity

curried

tupled

reversed

memoized

isMemoized

andThen

compose1

compose2

compose3

compose4

Interface Function4<T1,T2,T3,T4,R>