打印出简单的空心金字塔

package Test;

import java.util.Scanner;

public class test17 {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        System.out.println("请输入你想要打印金字塔的层数:");
        int num=sc.nextInt();
        for (int j=1;j<=num;j++){
            for (int k=1;k<=num-j;k++){
                System.out.print(" ");
            }
            for (int i=1;i<=j*2-1;i++){
                if (i==1||i==j*2-1||j==num){
                    System.out.print("*");
                }else {
                    System.out.print(" ");
                }
           }
            System.out.println();
        }
    }
}