【转载】java继承 初始化顺序

原文地址：http://blog.csdn.net/yunzhongguwu005/article/details/9698717

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package Study.Initialization;



class Base{

private String str1=init("str1");

private String str2=init("str2");

public static String str3=init("static str3");



public Base(String str1,String str2){

System.out.println("Run Construction Base");

this.str1=str1;

this.str2=str2;

}



protected static String init(String str){

System.out.println(str);

return str+" init";

}

}



class Derived extends Base{

private String str4=init("str4");

public static String str5=init("static str5");

public Derived(String str1,String str2,String str4){

super(str1,str2);

System.out.println("Run Construction Derived");

this.str4=str4;

}

}



public class extendInitialization {

public static void main(String[] args) {

System.out.println("run extendInitialization.main()");

Derived d=new Derived("construction str1","construction str2","construction str4");

System.out.println("----------------------------------------");

Derived d2=new Derived("construction str11","construction str22","construction str44");

}



}

运行结果:
run extendInitialization.main()

static str3

static str5

str1

str2

Run Construction Base

str4

Run Construction Derived

----------------------------------------

str1

str2

Run Construction Base

str4

Run Construction Derived

总结:

Derived的初始化顺序:

1.按定义时的顺序初始化基类的static成员

2..按定义时的顺序初始化扩展类的static成员

(以上两条是对第一次定义扩展类对象时运行)

3.按定义时顺序执行基类的指定初始化

4.执行基类的构造函数

5 按定义时的顺序执行扩展类的指定初始化

6.行扩展类的构造函数