public class test {
    public static void main(String[] args) {
        //调用Person类的无参构造器
        Person p = new Person();//初始化
    }
}

class Person{
    String name;
    int age;

    public Person(){
        System.out.println("初始化");
    }

    public Person(String name){
        this.name = name;
    }

    public Person(int age){
        this.age = age;
    }

    public Person(String name, int age){
        this.name = name;
        this.age = age;
    }
}