this and super

this 和 super 的区别：this, 先从本类找属性和方法，本类找不到再从父类找。super, 从父类找。

this 和 super 都可以调用构造方法，所以this() 和 super() 不可以同时出现。

public class Person {
}

public class Student extends Person {
    String name;
    public Student(String name) {
        super();
//        this();
    }
    public Student() {}
}

---

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class FatherClass {
    public int value;
    public void f() {
        value = 100;
        System.out.println("FatherClass,value = " + value);
    }
}

class ChildClass extends FatherClass {
    public int value;
    public void f() {
        super.f();
        value = 200;
        System.out.println("ChildClass,value = " + value);
        System.out.println(value);
        System.out.println(super.value);
    }
}

public class Demo {
    public static void main(String[] args) {
        ChildClass cc = new ChildClass();
        cc.f();
    }
}

画图分析：

 

 问题：

class Person {
    public String name;
    public String location;
    Person (String name) {
        this.name = name;
        location = "beijing";
    }
    Person (String name, String location) {
        this.name = name;
        this.location = location;
    }
    public String info() {
        return "name:" + name + ",location:" + location;
    }
}

class Student extends Person {
    private String school;
    Student(String name, String school) {
        // 这个地方应该调用父类无参的构造方法，但父类没有无参的构造方法，但实际上并没有调用，下面的"xxx"可以打印出来。？
        this(name, "benjing",school);
    }
    public Student(String name, String location, String school) {
        super(name, location);
        this.school = school;
    }
}

public class Demo {
    public static void main(String[] args) {
        new Student("c", "s1");
        System.out.println("xxx");
    }
}