Java Calendar

import java.text.DateFormatSymbols;
import java.util.Calendar;
import java.util.Locale;

public class Main {

  private static Locale locale = Locale.getDefault();
  private static String[] weekdays = DateFormatSymbols.getInstance(locale).getShortWeekdays();
  private static StringBuilder sb = new StringBuilder();

  public static void main(String[] args) throws Exception {
    Calendar calendar = Calendar.getInstance(locale);

    for (int i = Calendar.JANUARY; i <= Calendar.DECEMBER; i++) {
      calendar.set(Calendar.MONTH, i);
      printCalendar(calendar);
    }
    System.out.println(sb);
  }

  private static void printCalendar(Calendar calendar) {
    int week = calendar.getActualMaximum(Calendar.DAY_OF_WEEK);
    int maxDayOfMonth = calendar.getActualMaximum(Calendar.DATE);
    
    String era = calendar.getDisplayName(Calendar.ERA, Calendar.ALL_STYLES,  locale);
    int year = calendar.get(Calendar.YEAR);
    String month = calendar.getDisplayName(Calendar.MONTH, Calendar.ALL_STYLES, locale);
    sb.append(String.format("%1$s %2$d %3$s\r\n", era, year, month));
    
    for (String weekStr : weekdays) {
      sb.append(weekStr).append('\t');
    }

    calendar.set(Calendar.DATE, 1);
    int weekOfYear = calendar.get(Calendar.WEEK_OF_YEAR);
    int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK) - 2;
    int modWeek = (week - dayOfWeek) % week;

    for (int i = -dayOfWeek; i <= maxDayOfMonth; i++) {
      if ((week + i) % week == modWeek) {
        sb.append("\r\n").append(weekOfYear).append('\t');
        weekOfYear++;
      }
      if (i > 0) {
        sb.append(String.format("%d\t", i));
      } else {
        sb.append("\t");
      }

    }
    sb.append("\r\n\r\n");
  }

}