java基础编程60题之29

package com.xijiaopractice;


public class Test29 {
/*
* 求一个3*3矩阵对角线元素之和
*/
public static void main(String[] args) {
int[][] a={{1,2,3},{4,5,6},{7,8,9}};
int sum=0;
int sum2=0;
for (int i = 0; i < a.length; i++) {
for (int j = 0; j <a[0].length; j++) {
if(i==j){
sum+=a[i][j];
}
if(i+j==a.length-1){
sum2+=a[i][j];
}
}
}
System.out.println(sum);
System.out.println(sum2);
}
}