public class ChildA extends Father {

    void add() {

        System.out.println("A中的ADD");

    }

}

public class ChildB extends Father {

    void add() {

        System.out.println("B中的ADD");

    }

}

import org.apache.catalina.filters.AddDefaultCharsetFilter;

public class Father {

    public Father() {

        System.out.println(this);

    }

    void add() {

        System.out.println("父类中的ADD");

    }

}

public class Main {

    public static void main(String[] args) {

        Father a = new ChildA();

        a.add();

    }

}

public class Father1 {

    private int a = 10;

    Father1() {

        System.out.println(this instanceof Son);

        System.out.println(this.a);

        System.out.println(((Son) this).a);

        System.out.println(this.getClass().getName());

    }

    public static void main(String[] args) {

        Father1 s = new Son();

        System.out.println(s.a);

    }

}

class Son extends Father1 {

    public int a = 0;

    public int b = 1;

    public Son() {

        //隐式调用super();

        super();

        System.out.println("Son类中执行："+this);

    }

}