JavaDailyReports10_20

 1 package varycode;
 2 class Grandparent
 3 {
 4     public Grandparent()
 5      {
 6
 7             System.out.println("GrandParent Created.");
 8
 9     }
10
11
12     public Grandparent(String string)
13     {
14
15             System.out.println("GrandParent Created.String:" + string);
16
17     }
18
19 }
20
21
22
23 class Parent extends Grandparent
24 {
25
26
27     public Parent()
28      {
29
30             //super("Hello.Grandparent.");
31
32             System.out.println("Parent Created");
33
34          // super("Hello.Grandparent.");
35
36       }
37
38 }
39
40
41
42 class Child extends Parent
43 {
44
45
46     public Child()
47      {
48
49         System.out.println("Child Created");
50
51      }
52
53 }
54
55
56
57 public class TestInherits
58 {
59
60
61     public static void main(String args[])
62      {
63
64             Child c = new Child();
65
66   }
67
68 }

结论：在子类中调用super()方法，必须把调用语句放在子类构造的第一句，构造函数是实现初始化功能的，从子类一定要开始向父类实现构造方法。

二、

 1 package varycode;
 2 public class ExplorationJDKSource {
 3
 4     /**
 5      * @param args
 6      */
 7     public static void main(String[] args) {
 8         System.out.println(new A());
 9     }
10
11 }
12
13 class A{}

默认调用super类的hash值

---