入门练习，打印一个椭圆，效果如下  

      ***

  *         *

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

public class ellipse {
    public static void main(String[] args) {
        System.out.println("   *** ");
        System.out.println(" *     *");
        for (int i = 0; i <6; i++) {
            System.out.println("*       *");
        }
        System.out.println(" *     *");
        System.out.println("   *** ");
    }
}