docs: protected static String formatDateStr(String startDate, String strDays) {
  
          // Initial Calendar object
          Calendar cal = Calendar.getInstance();
          int days;
          startDate = startDate.replaceAll("/", "");
          try {
              days = Double.valueOf(strDays).intValue();
              // Set date with input value
              cal.set(Integer.parseInt(startDate.substring(0, 4)), Integer.parseInt(startDate.substring(4, 6)) - 1, Integer.parseInt(startDate.substring(6)));
              cal.add(Calendar.DATE, days);
              // translatet to yyddd format
              return String.format("%1$02d%2$03d", cal.get(Calendar.YEAR) % 100, cal.get(Calendar.DAY_OF_YEAR));
          } catch (Exception e) {
              // if tranlate failed, then use default value for date
              // sbError.append("! Waring: There is a invalid date [").append(startDate).append("]\r\n");
              return "-99"; //formatDateStr(defValD);
          }
  
      }