输入#的个数:

 /*输出:
#  #  #  #
#           #
#           #
#  #  #  #
*/

import java.util.Scanner;


public class Rectangle1 {
	public void DoDraw(int n){
		//String str ="";
		for(int i = 0;i < n;i++){
			for(int j = 0;j < n;j++){
				if(j == 0 || j == n - 1 || i == 0 || i == n - 1){
					System.out.print("# ");
				}else{
					System.out.print("  ");
				}
			}
			System.out.println();
		}
		//return str;
	}
	
	public static void main(String[]args){
		Scanner in = new Scanner(System.in);
		System.out.println("请输入正方形的边长:");
		int n =in.nextInt();
		Rectangle1 r = new Rectangle1();
		//System.out.print(r.DoDraw(n));
		r.DoDraw(n);
	}
}