Java面向对象抽象类实例练习

abstract class Animal
{
    abstract void eat();
}

class Cat extends Animal
{
    void eat()
    {
        System.out.println("eat fish");
    }
}

class Dog extends Animal
{
    void eat()
    {
        System.out.println("gnaw bone");
    }
}

class Pig extends Animal
{
    void eat()
    {
        System.out.println("eat rice");
    }
}

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