用Java遞歸來求N的階層

public class Du {

public static void main(String[] args) {
long fac = fac(n);
System.out.println("n的階乘為:" + fac);
}

public static long fac(int n){
if(n == 1){
return 1;
}else{
return fac(n-1) * n;
}
}

}