class ByteUtil {

    public static boolean isInteger(final byte[] asciiBuffer, final int offset, final int length)
    {
        for (int i = 0; i < length; i++)
        {
            if (!isAsciiDigit(asciiBuffer[offset + i]))
            {
                return false;
            }
        }

        return true;
    }

}

class ByteUtilTest {

        @Test
        public void shouldConfirmIsNotIntegerValue() throws UnsupportedEncodingException
        {

            final byte[] bytes = "1;3".getBytes(StandardCharsets.US_ASCII);
            assertFalse(ByteUtil.isInteger(bytes, 0, bytes.length));
        }

}