Initializer block.

Ref:　　Initializing Fields

　　Instance initializers are permitted to refer to the current object via the keyword this,Ref:　　Instance Initializers

 1 /*

 2 Initializer blocks,have the same capability as 'constructor',that is, they can use to initialze instance members.

 3 We use 'initialzer blocks',because all the instances of the class can have the same characteristic,such as 'cry'.

 4 */

 5 package kju.obj;

 6 

 7 import static kju.print.Printer.*;

 8 class InitializerBlock {

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

10         Person p = new Person();

11         Person lily = new Person("Lily", 21);

12         printHr();

13         lily.cry();

14         /*prints begin:

15         name = null is crying

16         name = null is crying

17 

18         -----------------------------------

19         name = Lily is crying

20         :prints ends*/

21     }

22 }

23 

24 class Person {

25     {

26         cry();

27     }

28 

29     public Person() {

30         

31     }

32 

33     public Person(String name) {

34         this.name = name;

35     }

36 

37     public Person(String name, int age) {

38         this(name);

39         this.age = age;

40     }

41 

42     public void cry() {

43         println("name = " + name + " is crying");

44     }

45 

46     private String name;

47     private int age;

48 }