java/w6/AnimalSystem.java

package java01;
abstract class Animal {
    public abstract void makeSound();
}
interface Swimmable {
    void swim();
}
class Dog extends Animal implements Swimmable {
    @Override
    public void makeSound() {
        System.out.println("狗：汪汪汪");
    }

    @Override
    public void swim() {
        System.out.println("狗会游泳");
    }
}
class Cat extends Animal {
    @Override
    public void makeSound() {
        System.out.println("猫：喵喵喵");
    }
}

public class AnimalSystem {
    public static void main(String[] args) {
        Animal animal1 = new Dog();
        Animal animal2 = new Cat();
        animal1.makeSound();
        animal2.makeSound();

        System.out.println("----------");
        if (animal1 instanceof Swimmable) {
            Swimmable swimmer = (Swimmable) animal1;
            swimmer.swim();
        }

        if (animal2 instanceof Swimmable) {
            Swimmable swimmer = (Swimmable) animal2;
            swimmer.swim();
        } else {
            System.out.println("猫不会游泳");
        }
    }
}