star shape. 

  **   
 **** 
******
******
 **** 
  ** 
  
  
  public static void main(String[] args) {
        
        System.out.println("  **  ");
        System.out.println(" **** ");
        System.out.println("******");
        System.out.println("******");
        System.out.println(" **** ");
        System.out.println("  **  ");