code: public String printISO8601Date()
    {
      CharBuffer cb = new CharBuffer();
  
      if (_year > 0) {
        cb.append((_year / 1000) % 10);
        cb.append((_year / 100) % 10);
        cb.append((_year / 10) % 10);
        cb.append(_year % 10);
        cb.append('-');
        cb.append(((_month + 1) / 10) % 10);
        cb.append((_month + 1) % 10);
        cb.append('-');
        cb.append(((_dayOfMonth + 1) / 10) % 10);
        cb.append((_dayOfMonth + 1) % 10);
      }
  
      return cb.toString();
    }
docs: Prints just the date component of ISO 8601