Doing XOR with many byte values - am I stupid?

Question

Hi,
I am having a problem by using the Java XOR Operator.
Sonething, call it module, delivers me an array of bytes. It includes different byte values and in the last field the checksum. The checksum you can get by doing:
(((1st Databyte XOR 2nd Databyte) XOR 3rd Databyte) XOR 4th Databyte) XOR ....
and so on. So I wrote the piece of code:
byte checksum = ((Integer)dataVector.get(0)).byteValue();
for(int i = 1; i < dataVector.size()-1; i++){
  checksum= (byte)(checksum^ ((Integer)dataVector.get(i)).byteValue());
if(checksum == ((Integer)dataVector.get(dataVector.size()-1)).byteValue())
  System.out.println("Yeah! Got it!");OK, it's a Vector, i see, but anyway I am handling with byte values so that doesn't matter.
So please say there is a mistake in the code.

Answer 1

I would implement it a little differently but your approach is correct too. Examine this small program:public class Checksum {
    // my way
    static boolean check(byte[] b) {
     byte checksum = 0;
     for (int i = 0; i < b.length; i++) {
         checksum ^= b;
     return checksum == 0;
// your way
static boolean check2(byte[] b) {
     byte checksum = b[0];
     for (int i = 1; i < b.length - 1; i++) {
     checksum ^= b[i];
     return checksum == b[b.length - 1];
public static void main(String[] args) {
     // 98 is all the other numbers XOR'ed together:
     byte[] array = {34, 124, -45, 76, 9, 71, -34, -56, -5, 98};
     System.out.println("Check1: " + check(array));
     System.out.println("Check2: " + check2(array));
// introduce a small mistake in the first element:
byte[] wrongArray = {24, 124, -45, 76, 9, 71, -34, -56, -5, 98};
System.out.println("Check1: " + check(wrongArray));
System.out.println("Check2: " + check2(wrongArray));
}The output is what you'd expect: Check1: true
Check2: true
Check1: false
Check2: falseEither your checksum is not calculated the way you think it is or there's some other problem. Why do have a Vector of [i]Integers when you should be working with bytes?