code: private static List<String> getDaySpan(int startDay, int endDay, int month, int year) {
  
          List<String> result = new ArrayList<String>();
          String yearMonthStr = String.valueOf(year) + DATES[month];
          for (int i = startDay; i <= endDay; i++) {
              String dateStr = yearMonthStr + DATES[i];
              result.add(dateStr);
          }
          return result;
      }
docs: Calculate a span of days in the given year and month for the optimized date range search.<p>
  
  The result will contain dates formatted like "yyyyMMDD", for example "20080131".<p>
  
  @param startDay the start day
  @param endDay the end day
  @param month the month
  @param year the year
  
  @return a span of days in the given year and month for the optimized date range search