I made a labview program which sends data through serial port . I have 8 bytes , so 8 values .
Labview sends ASCII or binary data. It does NOT send String objects. You have a choice of how to send the data. If you need it in binary, send it in binary. It is a waste of effort to convert the binary value that labview has to a string in hex format and then have to convert that string back back to a binary value. It is even worse to wrap the string in a String instance.
You need to unwrap the string from the String instance, and call strtoul() on the string to get the byte value.