循环打印日历

输入年份和代表该年第一天是星期几的数字，打印该年每个月的日历
代码：
package com.im;

import java.util.Scanner;

public class dd {

public static void main(String[] args) {    // TODO Auto-generated method stub    Scanner input = new Scanner(System.in);    // Prompt the user to enter input    System.out.print("Enter a year: ");    int year = input.nextInt();    System.out.print("Enter the first day of the year: ");    int firstDay = input.nextInt();    int startDay = firstDay;    int numberOfDaysInMonth = 0;    // Display calendar for each month    for (int month = 1; month <= 12; month++) {      // Display Calendar title      System.out.print("          ");      switch (month) {      case 1:        System.out.println("January " + year);        numberOfDaysInMonth = 31;        break;      case 2:        System.out.println("Feburary " + year);        if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0))          numberOfDaysInMonth = 29;        else          numberOfDaysInMonth = 28;        break;      case 3:        System.out.println("March " + year);        numberOfDaysInMonth = 31;        break;      case 4:        System.out.println("April " + year);        numberOfDaysInMonth = 30;        break;      case 5:        System.out.println("May " + year);        numberOfDaysInMonth = 31;        break;      case 6:        System.out.println("June " + year);        numberOfDaysInMonth = 30;        break;      case 7:        System.out.println("July " + year);        numberOfDaysInMonth = 31;        break;      case 8:        System.out.println("August " + year);        numberOfDaysInMonth = 31;        break;      case 9:        System.out.println("September " + year);        numberOfDaysInMonth = 30;        break;      case 10:        System.out.println("October " + year);        numberOfDaysInMonth = 31;        break;      case 11:        System.out.println("November " + year);        numberOfDaysInMonth = 30;        break;      case 12:        System.out.println("December " + year);        numberOfDaysInMonth = 31;        break;      }      System.out.println("-----------------------------");      System.out.println(" Sun Mon Tue Wed Thu Fri Sat");      // Pad space before the first day of the month      int i = 0;      for (i = 0; i < startDay; i++)        System.out.print("    ");      for (i = 1; i <= numberOfDaysInMonth; i++) {        if (i < 10)          System.out.print("   " + i);        else          System.out.print("  " + i);        if ((i + startDay) % 7 == 0)          System.out.println();      }      System.out.println();      System.out.println();      // Get the start day for the next month      startDay = (startDay + numberOfDaysInMonth) % 7;    }}

}