Are there standardized generic functional interfaces in Java8?

Question

I wonder if and where somebody did the job of defining a set of generic functional interfaces to ease and standardize the usage of lambdas. I come from C# where the core libraries did the job.

I read about "BiFunction" and found it to be clumsy. Especially when extended to TriFunction etc.

I came up with the following:

public interface FI {
@FunctionalInterface
public interface Action<T> {
    void invoke(T arg1);
}
@FunctionalInterface
public interface Function0<TResult> {
    TResult invoke();
}
@FunctionalInterface
public interface Function1<Targ1, TResult> {
    TResult invoke(Targ1 arg1);
}
@FunctionalInterface
public interface Function2<Targ1, Targ2, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2);
}
@FunctionalInterface
public interface Function3<Targ1, Targ2, Targ3, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3);
}
@FunctionalInterface
public interface Function4<Targ1, Targ2, Targ3, Targ4, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3, Targ4 arg4);
}
@FunctionalInterface
public interface Function5<Targ1, Targ2, Targ3, Targ4, Targ5, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3, Targ4 arg4, Targ5 arg5);
}
@FunctionalInterface
public interface Function6<Targ1, Targ2, Targ3, Targ4, Targ5, Targ6, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3, Targ4 arg4, Targ5 arg5, Targ6 arg6);
}
@FunctionalInterface
public interface Function7<Targ1, Targ2, Targ3, Targ4, Targ5, Targ6, Targ7, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3, Targ4 arg4, Targ5 arg5, Targ6 arg6, Targ7 arg7);
}
@FunctionalInterface
public interface Function8<Targ1, Targ2, Targ3, Targ4, Targ5, Targ6, Targ7, Targ8, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3, Targ4 arg4, Targ5 arg5, Targ6 arg6, Targ7 arg7, Targ8 atg8);
}
@FunctionalInterface
public interface Function9<Targ1, Targ2, Targ3, Targ4, Targ5, Targ6, Targ7, Targ8, Targ9, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3, Targ4 arg4, Targ5 arg5, Targ6 arg6, Targ7 arg7, Targ8 atg8, Targ9 arg9);
}
@FunctionalInterface
public interface Function10<Targ1, Targ2, Targ3, Targ4, Targ5, Targ6, Targ7, Targ8, Targ9, Targ10, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3, Targ4 arg4, Targ5 arg5, Targ6 arg6, Targ7 arg7, Targ8 atg8, Targ9 arg9, Targ10 arg10);
}

}

Answer 1

In Java 8 Officially only exist 4 types of Functions.

  Consumer: Void function
  Function: receive argument return argument
  BiFunction: Receive 2 arguments return argument
  Predicate: receive argument return boolean

Here you can see some examples about it.

https://github.com/politrons/reactive/blob/master/src/test/java/stream/Functions.java