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();
}
}