Java實現遞歸階乘

public class Factorial{
    public static void main(String[] args){
        for (int i = -5; i <= 5; i++) {
            System.out.printf("%d! = %d\n", i, negative(i));
        }
    }

    // 判斷n是否為負數
    public static int negative(int n){
        if (n >= 0){
            return factorial(n);
        } else {
            return -factorial(-n);
        }
    }

    // 遞歸階乘函數
    public static int factorial(int n){
        if (n == 0){
            return 1;
        } else {
            return factorial(n-1) * n;
        }
    }
}