假设有这样一段代码：
public class Cat {
private String name;
private int age;
public String toString() {
return "Cat [name=" + name + ", age=" + age + ", weight=" + weight
+ "]";
}
public Cat(String name, int age) {
System.out.println("Cat构造函数开始执行");
this.name = name;
this.age = age;
}
{
System.out.println("非静态代码块开始执行");
weight=2.0;
}
private double weight = 2.8;
}
public class Tets02 {
/**
* @param args
*/
public static void main(String[] args) {
Cat cat= new Cat("波斯猫",2);
System.out.println(cat.toString());
}
}
得出来weight的值是2.8；
执行的过程是：
double weight；
weight=2.0//非静态代码块执行
weight=2.8
此时weight=2.8是发生在构造函数中的。
但是如果是：
public class Cat {
private String name;
private int age;
private double weight = 2.8;
public String toString() {
return "Cat [name=" + name + ", age=" + age + ", weight=" + weight
+ "]";
}
public Cat(String name, int age) {
System.out.println("Cat构造函数开始执行");
this.name = name;
this.age = age;
}
{
System.out.println("非静态代码块开始执行");
weight=2.0;
}
}
得到的结果是weight=2.0
说明初始化代码块与构造函数的地位平等，完全是按照代码先后来执行的