一个Java方法覆盖的小问题

 1 class SuperClass{

 2

 3 public SuperClass() {

 4     System.out.println("superclass ");

 5     show();

 6 }

 7 public void show() {

 8     System.out.println("super class show !");

 9 }

10 }

11 class Subclass extends SuperClass{

12

13     public Subclass() {

14         super();

15         super.show();

16         System.out.println("subclass ");

17         show();

18     }

19     public void show(){

20

21         System.out.println("sub class  show !");

22     }

23

24 }

25 public class Test {

26 public static void main(String[] args) {

27     Subclass sub = new Subclass();

28 }

29 }

为什么这个结果？？？？？