int val = Character.digit((char)lastChar, 8);
int val = Character.digit((char)last_char, 8);
  public int readOct()  {    int val = Character.digit((char)lastChar, 8);    val += Character.digit((char)read(), 8);    if(val < 0) {      throw new ParseError("octal must have 3 octdigits.");    }    val += Character.digit((char)read(), 8);    if(val < 0) {      throw new ParseError("octal must have 3 octdigits");    }    return val;  }