Calendarr.java

package datastructures;

public class Calendarr
{
	public static int day(int month, int day, int year) {
        int y = year - (14 - month) / 12;
        int x = y + y/4 - y/100 + y/400;
        int m = month + 12 * ((14 - month) / 12) - 2;
        int d = (day + x + (31*m)/12) % 7;
        return d;
    }

    // return true if it is leap year.......
    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 month = Integer.parseInt(args[0]);    // month (Jan = 1, Dec = 12)
        int year = Integer.parseInt(args[1]);     // year

        // months[i] = name of month i
        String[] months =
        	                               
        	{"January", "February", "March",
            "April", "May", "June",
            "July", "August", "September",
            "October", "November", "December"};

        // days[i] = number of days in month i
        int[] days = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

        // check for leap year
        if (month == 2 && isLeapYear(year)) days[month] = 29;


        // print calendar week names as header.......
        System.out.println("   " + months[month] + " " + year);
        System.out.println(" S  M Tu  W Th  F  S");

        // starting day of month
        int d = day(month, 1, year);

        // print the calendar
        for (int i = 0; i < d; i++)
            System.out.println("  ");
        for (int i = 1; i <= days[month]; i++) 
        {
        	System.out.printf("%2",i);
            
            if (((i + d) % 7 == 0) || (i == days[month])) 
            	System.out.println();
            
        }

    }
}