继承和多态（Example5_9）

class Animal{  void cry(){}

}

class Dog extends Animal{

 void cry(){  

 System.out.println("wang!wang!......");

 }

}

class Cat extends Animal{  

void cry(){

  System.out.println("miao~~miao~~...");

 }

}

public class Example5_9{

 public static void main(String arg[]){

  Animal animal;      

   animal=new Dog();       

  animal.cry();        

animal=new Cat();        

animal.cry();        

  }  

}