// 불가능!!!
public class A extends A1, A2 {}

public class Parents {
    int a = 100;
    void methodP() {
        System.out.println("parent method");
    }
}

public class Child extends Parents {
    int a = 1;
    // 어노테이션
    @Override
    void methodP() {
        System.out.println("child method");
    }
}

public static void main(String[] args) {
    Child ch = new Child();
    ch.methodP();
}

// 실행 결과 ===========
// child method

public class Child extends Parents {
    int a = 1;

    void methodC() {
        System.out.println(super.a);
        System.out.println(this.a);
    }
}

public static void main(String[] args) {
    Child ch = new Child();
    ch.methodC();
}

// 실행 결과 ===========
// 100
// 1

class Parent {
    int p;

    Parent(int n) {
        p = n;
    }
    Parent() {
        p = 100;
    }
}

class Child extends Parent {
    Child() {
        super(9999);
    }
}

class Child extends Parent{}

Parent p = new Parent();
Child ch = new Child();

// instanceof 메서드 활용 =======

p instanceof Parent; // true
ch instanceof Parent; // true
p instanceof Child; // false
ch instanceof Child; // true