Java Recursion in Lambda Expressions [duplicate]

Can anyone help me with this example? The recursion can be in the constructor but not outside. import

class recursion {
    int factorial_imp(int i) {
        if (i == 1) return 1;
        else return i * factorial_imp(i - 1);
    }
    Function < Integer, Integer > factorial_lambda;
    public static void main(String[] args) {
        new recursion();
    }
    public recursion() {
        factorial_lambda = (i) -> {
            if (i == 1) return 1;
            else return i * (factorial_lambda.apply(i - 1));
        };
        System.out.println(factorial_imp(5));
        System.out.println(factorial_lambda.apply(5));
    }
}