Java Question

If I have 4 by 4 matrix and I fill row and columns index 0 to 3 with 0 or 1 , but I want row and column 4 to be the sum of each row and column. How would I implement that?

Example; A 4 by 4 matrix with index 0 to 3 filled with 0's or 1's

0 1 0

1 0 1

0 0 1

The matrix after the sum of each row and column is calculated (row 4 and column 4)

0 1 0 1 -> where 1 is the sum

1 0 1 2 -> where 2 is the sum

0 0 1 1 -> where 1 is the sum

1 1 2 ? -> and the bottom right element is the sum of the 4th column and the 4th row