How can I print the pattern without filling inside of it?

I want to print a butterfly like this using java:

*     *
**   **
* * * *
* *** *
* * * *
**   **
*     *

However the code below prints this pattern if n=4:

*     *
**   **
*** ***
*******
*** ***
**   **
*     *

How can I print the butterfly without printing inside of it ? I took this source code from http://solvedpatterns.blogspot.com/2016/07/ButterFly.html

import java.util.Scanner;
public class Soru2 {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        System.out.println("Enter n value");
        int n=sc.nextInt();
        int sp=2*n-1;
        int st=0;
        for(int i=1;i<=2*n-1;i++){
            if(i<=n){
                sp=sp-2;
                st++;
            }
            else{
                sp=sp+2;
                st--;
            }
            for(int j=1;j<=st;j++){
                System.out.print("*");
            }
            for(int k=1;k<=sp;k++){
                System.out.print(" ");
            }
            for(int l=1;l<=st;l++){
                if(l!=n)
                    System.out.print("*");
            }
            System.out.println();
        }
    }
}