1. class Egg2
   
2. {
   
3. protected class Yolk
   
4. {
   
5. public Yolk()
   
6. {
   
7. System.out.println("Egg2.Yolk()");
   
8. }
   
9. public void f()
   
10. {
    
11. System.out.println("Egg2.Yolk.f()");
    
12. }
    
13. }
    
14. private Yolk y = new Yolk();
    
15. public Egg2()
    
16. {
    
17. System.out.println("New Egg2()");
    
18. }
    
19. public void insertYolk(Yolk yy) { y = yy; }
    
20. public void g() { y.f(); }
    
21. }
    
22. 
    
23. public class BigEgg2 extends Egg2
    
24. {
    
25. public class Yolk extends Egg2.Yolk
    
26. {
    
27. public Yolk()
    
28. {
    
29. System.out.println("BigEgg2.Yolk()");
    
30. }
    
31. public void f()
    
32. {
    
33. System.out.println("BigEgg2.Yolk.f()");
    
34. }
    
35. }
    
36. public BigEgg2() { insertYolk(new Yolk()); }
    
37. public static void main(String[] args)
    
38. {
    
39. Egg2 e2 = new BigEgg2();
    
40. e2.g();
    
41. }
    
42. }
    

复制代码

出结果是
Egg2.Yolk()
New Egg2()
Egg2.Yolk()
BigEgg2.Yolk()
BigEgg2.Yolk.f()

求分析

自个参悟出来了 。。