diagonal difference hackerrank solution in code example

Example: diagonal difference hackerrank solution in java 8 using list

public static int diagonalDifference(List<List<Integer>> arr) {
    // Write your code here
    int leftd=0;
    int rightd=0;
    int n=arr.size();
    for(int i=0;i<n;i++)
    {
        leftd+=arr.get(i).get(i);
        rightd+=arr.get(i).get(n-i-1);
    }
    int absd=Math.abs(leftd-rightd);
    return absd;

    }