如题

import java.util.*;
public class zy1 {
    public static void main (String args[]){
        int n=0;
       int i,j;
     int a[][] = new int[n][n];
     Scanner in = new Scanner(System.in);
     n = in.nextInt();
        for ( i = 0; i < n; i++) {
            for ( j = 0; j < n; j++) {
            }
        }
        for ( i = 0; i < n; i++) {
            for ( j = 0; j < n; j++) {
                System.out.print(a[i][j] + " ");
            }
            System.out.println("");
        }
    }
}
这段程序 还需要添加什么？

import java.util.*;
public class zy1 {
    public static void main (String args[]){
        int n=0;
       int i,j;
     int a[][] = new int[n][n];
     Scanner in = new Scanner(System.in);
     n = in.nextInt();
        for ( i = 0; i < n; i++) {
            for ( j = 0; j < n; j++) {
            }
        }
        for ( i = 0; i < n; i++) {
            for ( j = 0; j < n; j++) {
                System.out.print(a[i][j] + " ");
            }
            System.out.println("");
        }
    }
}

在上面标记的for循环中

找出i=j的所有项，
那些数属于哪条对角线应该清楚了吧。。。

再找出i=(n-1-j)的所有项

if(i==j || i==(n-1-j))
   sum +=a[i][j];