Java开发练习1 求一个n阶方阵对角线元素之和。

import java.util.*;
public class Fangzhen {

public static void main(String[] args) {
// TODO Auto-generated method stub
int n = 0;
Scanner num = new Scanner(System.in);
System.out.println("请输入阶数：");
n = num.nextInt();
int[][] a =new int

;
Scanner reader = new Scanner(System.in);
System.out.println("请输入元素：");
for(int i = 0;i<n;i++){
for(int j = 0;j<n;j++){
a[i][j] = reader.nextInt();
}

}
int nm1,nm2,sum1 = 0,sum2 = 0,sum=0;
for(int i = 0;i<n;i++){
nm1 = a[i][i];
sum1 = sum1 + nm1;
}
for(int i = 0,j=n-1;i<n;i++,j--){
nm2 = a[i][j];
sum2 = sum2+nm2;
}
sum = sum1+sum2;
System.out.println("对角线上元素之和是"+sum);
}

}