Java实现简单的正方形

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner (System.in);
        int n = sc.nextInt();
        int count = 1;
        int[][] a = new int[n][n];
        for(int i = 0 ; i <=a.length/2;i++) {
            for(int j = i ;j <a.length-i;j++) {
                a[i][j] = count++; 
            }
            for(int k = i+1;k<a.length-i;k++) {
                a[k][a.length-i-1] = count++;
            }
            for(int j = a.length-i-2;j>=i;j--) {
                a[a.length-i-1][j] = count++;
            }
            for(int k = a.length-i-2 ; k>=i+1 ; k--) {
                a[k][i] = count++;
            }
        }
        for(int i = 0 ; i <a.length;i++) {
            for(int j = 0 ;j<a[i].length;j++) {
                System.out.printf("%4d",a[i][j]);
            }
            System.out.println();
        }
        System.out.println();
        
        
    }
}