java初始化

 1 package test;
 2 
 3 public class A extends B {
 4 
 5     int i;
 6     static int b;
 7     public D firstD = new D("A");
 8     public static C firstC = new C("A");
 9     public static C secondC;
10     {
11         System.out.println("i:"+i);//此时i未初始化，为默认值0
12         System.out.println("b:"+b);
13         System.out.println(secondC);
14     }
15     A(){
16         
17         System.out.println("here is A");
18         i = 1;
19         b = 1;
20     }
21     
22     public static void main(String[] args) {
23         // TODO 自动生成的方法存根
24         new A();
25     }
26 
27 }
28 
29 class B {
30     public static C CinB = new C("B");
31     public D DinB = new D("B");
32     B(){
33         System.out.println("here is B");
34     }
35 }
36 
37 class C {
38     C(String source){
39         System.out.println("here is C from"+source);
40     }
41 }
42 
43 class D {
44     D(String source){
45         System.out.println("here is D from"+source);
46     }
47 }