Java for loop display calendar

import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner input = new Scanner(System.in);

    System.out.print("Enter year: ");
    int year = input.nextInt();
    System.out.print("Enter first day of the year: ");
    int day = input.nextInt();

    String header;/*from  w  ww  . j  a  v  a2 s . c om*/
    System.out.println();
    for (int month = 1; month <= 12; month++) {
      header = "";
      // Concatenate current month string to header
      switch (month) {
      case 1:
        header += "January ";
        break;
      case 2:
        header += "February ";
        break;
      case 3:
        header += "March ";
        break;
      case 4:
        header += "April ";
        break;
      case 5:
        header += "May ";
        break;
      case 6:
        header += "June ";
        break;
      case 7:
        header += "July ";
        break;
      case 8:
        header += "August ";
        break;
      case 9:
        header += "September ";
        break;
      case 10:
        header += "October ";
        break;
      case 11:
        header += "November ";
        break;
      case 12:
        header += "December ";
        break;
      }
      // Concat current year to header
      header += year + "";

      // Center header string
      for (int b = 0; b < 23 - (header.length() / 2); b++) {
        System.out.print(" ");
      }

      // Display header and days of the week string
      System.out.println(header + "\n-----------------------------------------------\n "
          + "Sun    Mon    Tue    Wed    Thu    Fri    Sat");

      // Compute day of the week
      day %= 7;
      for (int b = 0; b <= day * 7; b++) {
        System.out.print(" ");
      }

      // Compute last day of present month
      int lastDay = 0;
      if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12)
        lastDay += 31;
      else if (month == 4 || month == 6 || month == 9 || month == 11)
        lastDay += 30;
      else { // Test for leap year
        if (((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0))
          lastDay += 29;
        else
          lastDay += 28;
      }

      // Display calendar for current month
      for (int d = 1; d <= lastDay; d++) {
        // Add a black space before numbers less than 10
        if (d < 10)
          System.out.print(" ");
        // Start new line after Saturday
        if (day % 7 == 6)
          System.out.print(d + "\n ");
        else {
          System.out.print(d + "     ");
          if (d == lastDay)
            System.out.println();
        }
        day++;

      }
      System.out.println();
    }
  }
}