// 动物叫声系统

// 抽象类 Animal
abstract class Animal {
    // 抽象方法 makeSound()
    public abstract void makeSound();
}

// 接口 Swimmable
interface Swimmable {
    void swim();
}

// Dog 类继承 Animal 并实现 Swimmable 接口
class Dog extends Animal implements Swimmable {
    @Override
    public void makeSound() {
        System.out.println("Dog: Woof! Woof!");
    }
    
    @Override
    public void swim() {
        System.out.println("Dog is swimming");
    }
}

// Cat 类继承 Animal，但不实现 Swimmable 接口
class Cat extends Animal {
    @Override
    public void makeSound() {
        System.out.println("Cat: Meow! Meow!");
    }
}

// 测试类
public class W6作业 {
    public static void main(String[] args) {
        // 测试多态调用
        Animal animal1 = new Dog();
        Animal animal2 = new Cat();
        
        System.out.println("Testing polymorphic calls:");
        animal1.makeSound();
        animal2.makeSound();
        
        // 测试 Swimmable 接口
        System.out.println("\nTesting Swimmable interface:");
        if (animal1 instanceof Swimmable) {
            ((Swimmable) animal1).swim();
        } else {
            System.out.println("Dog cannot swim");
        }
        
        if (animal2 instanceof Swimmable) {
            ((Swimmable) animal2).swim();
        } else {
            System.out.println("Cat cannot swim");
        }
    }
}