display month calendar in java

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

public class MonthCalender {

public final static String[] monthcalender = {
"January", "February", "March", "April", "May", "June", "July",
"August", "September", "October", "November", "December"};

public final static int daysinmonths[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

private void displayMonth(int month, int year) {

// The number of days to leave blank at
// the start of this month.

int blankdays = 0;
System.out.println("  " + monthcalender[month] + " " + year);

if (month < 0 || month > 11) {
throw new IllegalArgumentException(
"Month " + month + " is not valid and must lie in between 0 and 11");
}

GregorianCalendar cldr = new GregorianCalendar(year, month, 1);
System.out.println("Sunday Monday Tuesday Wednesday Thursday Friday Saturday");

// Compute how much to leave before before the first day of the month.
// getDay() returns 0 for Sunday.

blankdays = cldr.get(Calendar.DAY_OF_WEEK)-1;
int daysInMonth = daysinmonths[month];

if (cldr.isLeapYear(cldr.get(Calendar.YEAR)) && month == 1) {

++daysInMonth;
}

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

for (int i = 1; i <= daysInMonth; i++) {

// This "if" statement is simpler than messing with NumberFormat
if (i<=9) {
System.out.print(" ");
}
System.out.print(i);

if ((blankdays + i) % 7 == 0) { // Wrap if EOL
System.out.println();
}
else {
System.out.print(" ");
}
}
}

/**
     * Sole entry point to the class and application.
     * @param args Array of String arguments.
     */
    public static void main(String[] args) {

int mon, yr;
MonthCalender moncldr = new MonthCalender();

if (args.length == 2) {
moncldr.displayMonth(Integer.parseInt(args[0])-1, Integer.parseInt(args[1]));
}
else {
Calendar todaycldr = Calendar.getInstance();
moncldr.displayMonth(todaycldr.get(Calendar.MONTH), todaycldr.get(Calendar.YEAR));
}
}
}