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();
     }
 }