What is the purpose of "^= "operator in Java?

Question

I was studying on leetcode for an interview. There were a question about finding missing number unpaired in array. I solved it by using HashSet. But i saw the below solution which is more efficient than mine.My question is that what the logic XOR of a ^= nums[i] means ?

int a = 0;
for (int i = 0; i < nums.length; i++) {
    a ^= nums[i];
}
return a;

Answer 1

You are now familiar by all answers that ^= is the XOR-and-becomes operator.

As x ^ x == 0 and x ^ 0 == x doing a cumulative XOR will remove twice occurring duplicates and the result will be the sole single occurrence.

3 ^ 5 ^ 3 ^ 7 ^ 5 = (3 ^ 3) ^ (5 ^ 5) ^ 7 = 0 ^ 0 ^ 7 = 7
3   6   5   2   7  <--- stepwise accumulated: 3=1+2, 5=1+4, 7=1+2+4

XOR is an interesting commutative and associative function "bit is different" as it does not loose information,

z = x ^ y   =>   y = z ^ x