Print stars in "X" shape using Java

Stars.java

class Stars {
    
    public static void main(String args[]) {

        int p = 20, diff = 2;

        for (int i = p, d = -diff; i <= p; i += d) {

            while ((i == 0 && d != diff) || i == 1 && d != diff)d = diff;

            for (int k = 0; k < (p - i) / 2; k++) System.out.print(" ");

            for (int k = 0; k <= i; k++) System.out.print("*");

            System.out.println(" ");
        }
    }
}