Calendar java in pgm

Calendar.java

public class Calendar

{

 public static int day(int M, int D, int Y)

{

        int y = Y - (14 - M) / 12;

        int x = y + y/4 - y/100 + y/400;

        int m = M + 12 * ((14 - M) / 12) - 2;

        int d = (D + x + (31*m)/12) % 7;

        return d;

    }

                  public static boolean isLeapYear(int year)

                  {

        if  ((year % 4 == 0) && (year % 100 != 0)) return true;

        if  (year % 400 == 0) return true;

        return false;

    }

     public static void main(String[] args)

    {

        int M = Integer.parseInt(args[0]);   

        int Y = Integer.parseInt(args[1]);   

         String[] months = {

             "",                              

             "January", "February", "March",

             "April", "May", "June",

             "July", "August", "September",

             "October", "November", "December"

        };

        int[] days = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

                     if (M == 2 && isLeapYear(Y)) days[M] = 29;

                    StdOut.println("   " + months[M] + " " + Y);

        StdOut.println(" S  M Tu  W Th  F  S");

        int d = day(M, 1, Y);

                     for (int i = 0; i < d; i++)

            StdOut.println("   ");

        for (int i = 1; i <= days[M]; i++)

        {

            StdOut.printf("%2d ", i);

            if (((i + d) % 7 == 0) || (i == days[M]))

            StdOut.println();

  }

            }

        }