Java继承和方法调用问题

Question

class Exam9 {
    public static void main(String[] args) {
        people p=new graduate();}
}
class people{
    String name;
    int age;
    people(){}
    people(String name,int age){
        this.name=name;
        this.age=age;
        System.out.println("In people");	}
}
class student extends people{
    String school;
    student(){
        this(null,0,null);
        System.out.println("In student1");	}
    student(String name,int age,String school){
        super(name,age);
        this.school=school;
        System.out.println("In student2");	}
}
class graduate extends student{
    graduate(){
        System.out.println("In graduate");	}
}

输出结果

In people
In student2
In student1
In graduate

想问一下为什么会先从In people开始依次输出，而不是直接输出 In graduate呢？

谢谢！

Answer 1

因为java构造方法，先构造基类，然后是你用 new graduate()调用的无参构造函数

所以整体顺序是，先调用people无参构造函数,再调用student无参构造函数

然后自定义构造函数就开始起作用了。