import java.util.*;
import java.text.*;

/** Print a month page.
 * Only works for the Western calendar. 
 */
public class CalendarPage {

    /** The names of the months */
    String[] months = {
        "January", "February", "March", "April",
        "May", "June", "July", "August",
        "September", "October", "November", "December"
    };

    /** The days in each month. */
    public final static int dom[] = {
            31, 28, 31, 30,    /* jan feb mar apr */
            31, 30, 31, 31, /* may jun jul aug */
            30, 31, 30, 31    /* sep oct nov dec */
    };

    /** Compute which days to put where, in the Cal panel */
    public void print(int mm, int yy) {
        /** The number of days to leave blank at the start of this month */
        int leadGap = 0;

        System.out.print(months[mm]);        // print month and year
        System.out.print(" ");
        System.out.print(yy);
        System.out.println(  );

        if (mm < 0 || mm > 11)
            throw new IllegalArgumentException("Month " + mm + " bad, must be 0-11");
        GregorianCalendar calendar = new GregorianCalendar(yy, mm, 1);

        System.out.println("Su Mo Tu We Th Fr Sa");

        // Compute how much to leave before the first.
        // getDay(  ) returns 0 for Sunday, which is just right.
        leadGap = calendar.get(Calendar.DAY_OF_WEEK)-1;

        int daysInMonth = dom[mm];
        if (calendar.isLeapYear(calendar.get(Calendar.YEAR)) && mm == 1)
            ++daysInMonth;

        // Blank out the labels before 1st day of month
        for (int i = 0; i < leadGap; i++) {
            System.out.print("   ");
        }

        // Fill in numbers for the day of month.
        for (int i = 1; i <= daysInMonth; i++) {

            // This "if" statement is simpler than fiddling with NumberFormat
            if (i<=9)
                System.out.print(' '),
            System.out.print(i);

            if ((leadGap + i) % 7 == 0)        // wrap if end of line.
                System.out.println(  );
            else
                System.out.print(' '),
        }
        System.out.println(  );
    }

    /** For testing, a main program */
    public static void main(String[] av) {
        int month, year;

        CalendarPage cp = new CalendarPage(  );

        // print the current month.
        if (av.length == 2) {
            cp.print(Integer.parseInt(av[0])-1, Integer.parseInt(av[1]));
        } else {
            Calendar c = Calendar.getInstance(  );
            cp.print(c.get(Calendar.MONTH), c.get(Calendar.YEAR));
        }
    }
}