code: protected Date parseNonNullDate(String str, ParsePosition pos)
     {
        Date result = null;
        for (int index = 0; index < m_formats.length; index++)
        {
           result = m_formats[index].parse(str, pos);
           if (pos.getIndex() != 0)
           {
              break;
           }
           result = null;
        }
        return result;
     }
docs: We have a non-null date, try each format in turn to see if it can be parsed.
  
  @param str date to parse
  @param pos position at which to start parsing
  @return Date instance