Declarative and imperative Factorial program

declarativeVsImperative

package math;
public class Factorial {
public static long declarativeFactorial(int n) {
assert n > 0 : "Argument must be greater than 0";
if (n == 1) return 1;
else return n * declarativeFactorial(n-1);
}
public static long imperativeFactorial(int n) {
assert n > 0 : "Argument must be greater than 0";
long result = 1;
for (int i = 2; i<= n; i++) {
result *= i;
}
return result;
}