这种情况应该怎么修改，，

package homework3;

import java.util.Scanner;

public class J {
    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        int n,sum1=0,sum2=0;
        n=in.nextInt();
        int [][]a=new int[n][n];
        for (int i = 0; i < n; i++)
        {
            for (int j = 0; j < n; j++)
            {
                a[i][j]=in.nextInt();
            }
        }
        for (int i = 0; i < n; i++)
                sum1+=a[i][i];
        for (int i = n-1; i >= 0; i++)
            sum2+=a[i][i];
        System.out.println(sum1+" "+sum2);
    }
}

下面那个for循环应该是i--，而不是i++