向上造型演示

package oo.day04;
//向上造型演示
public class UpDemo {
    public static void main(String[] args) {
        /*
        Eoo o1 = new Eoo();
        o1.e = 1;
        o1.show();
        */
        
        /*
        Foo o2 = new Foo();
        o2.f = 1;
        o2.say();
        o2.e = 2;
        o2.show();
        */
        
        Eoo o3 = new Foo(); //向上造型
        o3.e = 1;
        o3.show();
        //o3.f = 2; //编译错误，点出来什么，看引用的类型
    }
}

class Eoo{
    int e;
    void show(){
    }
}
class Foo extends Eoo{
    int f;
    void say(){
    }
}