Implement recursive lambda function using Java 8

I usually use (once-for-all-functional-interfaces defined) generic helper class which wraps the variable of the functional interface type.
This approach solves the problem with the local variable initialization and allows the code to look more clearly.

In case of this question the code will look as follows:

// @param <I> - Functional Interface Type
public class Recursive<I> {
    public I func;

public double factorial(int n) {

    Recursive<IntToDoubleFunction> recursive = new Recursive<>();
    recursive.func = x -> (x == 0) ? 1 : x * recursive.func.applyAsDouble(x - 1);

    return recursive.func.applyAsDouble(n);

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