一段代码看懂Java类的加载和初始化

先贴代码

class Base {
int a = numa();  
private static int c = numc(); 
static int b = numb();
static {
System.out.println("Base:static code block..");  
}
Base(){
System.out.println("Base:constructor..."); 
}

static int numa(){
System.out.println("Base:int a..."); 
return 1;
}
static int numb(){
System.out.println("Base:static int b...");
return 1;
}
static int numc(){
System.out.println("Base:private static int c...");
return 1;
}
}

class A extends Base{  
private static int l = numl();
private int m = numm();
static{  
System.out.println("A:static code block...");
}
A(){  
System.out.println("A:constructor..."); 
}   
static int numl() {  
System.out.println("A:static int l...");  
return 1;  
}  
int numm() {  
System.out.println("A:private int m...");  
return 1;  
}

}

public class Test{
public static void main(String[] args){
new A();
}
}

输出结果如下：

Base:private static int c...
Base:static int b...
Base:static code block..
A:static int l...
A:static code block...
Base:int a...
Base:constructor...
A:private int m...
A:constructor...

从输出结果很直观的看出初始化的顺序。静态到实例，父类到子类，实例化的时候构造器就开始工作了。

总结：先加载父类，再加载子类，然后初始化父类static，然后初始化子类static，然后执行父类构造函数，最后执行子类构造函数