Factorial.java

public class Factorial {
    static int fact(int n) { return n == 0 ? 1 : n * fact(n - 1); }
    public static void main(String[] args) {
        int n = args.length == 0 ? 1 : Integer.parseInt(args[0]);
        for(int i = 1; i <= n; i++) System.out.println(i + "! = " + fact(i));
    }
}