Java多态

public class Fu {
    
    int num = 10;
    public void method(){
        System.out.println("Fu....method");
    }

}
public class Zi extends Fu {
    int num = 20;

    @Override
   public void method() {
        System.out.println("Zi...method");
    }
    public void show(){
        System.out.println("Zi类特有的方法，show");
    }
}
public class TestPolymorpic {
    public static void main(String[] args) {
//        向上转型
        Fu f = new Zi();
        System.out.println(f.num);
        f.method();
//        向下转型，或者直接创造子类对象
        Zi z = (Zi) f;
        z.show();
    }
}


//   多态的用处

public class Test1Polymorphic {
    public static void main(String[] args) {
        useAnimal(new Cat());
        useAnimal(new Dog());
    }
    public static void useAnimal(Animal a){
        a.eat();

        if(a instanceof Dog){
            Dog dog = (Dog) a;
            dog.wacthHome();
        }


    }
}
abstract class Animal{
    public abstract void eat();
}
 class Dog extends Animal{
    @Override
    public void eat() {
        System.out.println("狗吃肉");
    }
    public void wacthHome(){
        System.out.println("狗特有方法");
    }
}
class Cat extends Animal{
    @Override
    public void eat() {
        System.out.println("猫吃鱼");
    }
}