Matrix

public class Matrix {
    public static void sum(int [] [] matrix){
        int sum = 0;

        for (int i = 0; i < matrix.length; i++) {
            for (int j = 0; j < matrix[i].length; j++) {
                System.out.printf(matrix [i] [j] + " ");
                sum += matrix[i][j];
            }
            System.out.println();

        }
        System.out.println("Sum is: " + sum);
    }
    public static void DiagonalSum(int [] [] matrix){
        int SumD1 = 0;
        int SumD2 = 0;

        for (int i = 0; i < matrix.length; i++) {
            SumD1 = matrix [i] [i];
            SumD2 = matrix [i] [matrix.length - 1 - i];
        }

        System.out.println("First diagonal sum is: " + SumD1);
        System.out.println("Second diagonal sum is: " + SumD2);


    }
    public static void main(String[] args){
        int [] [] matrix = new int [4] [4];

        matrix [0] [0] = 12;
        matrix [0] [1] = 10;
        matrix [0] [2] = 15;
        matrix [0] [3] = 18;
        matrix [1] [0] = 23;
        matrix [1] [1] = 42;
        matrix [1] [2] = 24;
        matrix [1] [3] = 31;
        matrix [2] [0] = 62;
        matrix [2] [1] = 56;
        matrix [2] [2] = 47;
        matrix [2] [3] = 17;
        matrix [3] [0] = 33;
        matrix [3] [1] = 49;
        matrix [3] [2] = 15;
        matrix [3] [3] = 19;

        sum(matrix);
        DiagonalSum(matrix);

    }
}