本文介绍了java中的内联初始化块的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我有一个班级
public class MyMain{
public static void main(String... arg){
Temp t = new Temp(){
{
System.out.println(" instance initialize");
}
};
}
}
class Temp{
int i;
{
i=9;
System.out.println("Static"+i);
}
Temp(){
System.out.println("Temp const "+i);
}
}
当我执行main方法时输出到:
When i execute the main method the output comes:
Static9
Temp const 9
instance initialize
理想情况下,块在构造函数之前执行,但是在构造函数之后调用内联初始化块。为什么?
Ideally, the blocks are executed before the constructor, but the inline initialization block is called after the Constructor. Why?
推荐答案
您正在创建 Temp的子类
。对于每个类,任何实例初始值设定项都在构造函数体之前执行 - 但是超类在子类初始化之前进行初始化。所以执行流程为:
You're creating a subclass of Temp
. For each class, any instance initializers are executed before the constructor body - but the superclass goes through initialization before the subclass initialization. So the execution flow is:
-
对象
$ b中的初始值设定项$ b -
对象中的构造函数体
-
Temp
- 构造函数体
Temp
- 匿名类中的初始值设定项
- 匿名类中的构造函数体(无)
- Initializers in
Object
- Constructor body in
Object
- Initializers in
Temp
- Constructor body in
Temp
- Initializers in anonymous class
- Constructor body in anonymous class (none)
我强烈建议您重构任何看起来像这样的代码 - 目标为了清晰而不是聪明。
I would strongly advise you to refactor any code which looked like this anyway - aim for clarity rather than cleverness.
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