private static char encodeASCIIDigits(char c, char c1) { if (HighLevelEncoder.isDigit(c) && HighLevelEncoder.isDigit(c1)) { return (char) ((c - 48) * 10 + (c1 - 48) + 130); } else { throw new IllegalArgumentException( (new StringBuilder("not digits: ")).append(c).append(c1).toString()); } }