return false;
return true;
  public boolean isLongConvertible()  {    char []buffer = _buffer;    int len = _length;    if (len == 0)      return false;    for (int i = 0; i < len; i++) {      char ch = _buffer[i];      if (! ('0' <= ch && ch <= '9'))        return false;    }    return true;  }