In an array, all the numbers are appearing 3 times(or odd no. of times) except one number,which appears once, Find that number using bit-manipulation? [closed]

I am following this video and @1.17.00, there is an explanation for solution which goes something like this:

lets say arr = {1,2,2,1,3,2,1}
1 -> 0001
2 -> 0010
2 -> 0010
1 -> 0001
3 -> 0011
2 -> 0010
1 -> 0001
summing bits -> 0044
n -> no. of repetion, which in this case is 3
modulo of the elements of sum by n -> 0044 % 3 = 0011 = 3
Hence 3 is the answer.

How to implement this in code in java?