Java 类加载顺序

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1、虚拟机在首次加载Java类时，会对静态初始化块、静态成员变量、静态方法进行一次初始化
2、只有在调用new方法时才会创建类的实例
3、类实例创建过程：按照父子继承关系进行初始化，首先执行父类的初始化块部分，然后是父类的构造方法；再执行本类继承的子类的初始化块，最后是子类的构造方法
4、类实例销毁时候，首先销毁子类部分，再销毁父类部分

先初始化父类的静态代码--->初始化子类的静态代码-->初始化父类的非静态代码--->初始化父类构造函数--->初始化子类非静态代码--->初始化子类构造函数

public class Parent {public static int t = parentStaticMethod2();{System.out.println("Parent: not static block");}static {System.out.println("Parent: static block");}public Parent() {System.out.println("Parent: constructor");}public static int parentStaticMethod() {System.out.println("Parent: static method 1");return 10;}public static int parentStaticMethod2() {System.out.println("Parent: static method 2");return 9;}@Overrideprotected void finalize() throws Throwable {// TODO Auto-generated method stubsuper.finalize();System.out.println("Parent: destory");}}

public class Child extends Parent {{System.out.println("Child: not static block");}static {System.out.println("Child: static block");}public Child() {System.out.println("Child: constructor");}public static int childStaticMethod() {System.out.println("Child: static method");return 1000;}@Overrideprotected void finalize() throws Throwable {// TODO Auto-generated method stubsuper.finalize();System.out.println("Parent: destory");}}

public class TestClassloader {public static void main(String[] args) {Parent.parentStaticMethod();}}

输出如下：

Parent: static method 2
Parent: static block
Parent: static method 1

public class TestClassloader {public static void main(String[] args) {Parent.parentStaticMethod();System.out.println("=====");Child child = new Child();}}

输出如下：

Parent: static method 2
Parent: static block
Parent: static method 1
=====
Child: static block
Parent: not static block
Parent: constructor
Child: not static block
Child: constructor

public class TestClassloader {public static void main(String[] args) {Child child = new Child();}}

输出如下：

Parent: static method 2
Parent: static block
Child: static block
Parent: not static block
Parent: constructor
Child: not static block
Child: constructor

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