多态的三个条件： 1、要有继承 2、要有重写 3、父类引用指向子类对象----java

/*
*多态的三个条件： 1、要有继承 2、要有重写 3、父类引用指向子类对象
*此类写法 可以扩展程序而改变最少
*/


class Animal
{
private String name ;
Animal(String name)
{
this.name = name;
}

public void enjoy()
{
System.out.println("叫声.......");
}
}
class Cat extends Animal
{
private String name;
private String eyeclor;
  Cat(String name,String eyeclor)
  {
  super(name);//调用父类构造方法
  this.eyeclor = eyeclor;
  }
  public void enjoy()//对父类方法的重写
  {
  System.out.println("猫声.......");
  }
}
class Dog extends Animal
{
private String name;
private String furclor;
Dog(String name,String furclor)
{
super(name);
this.furclor = furclor; 
}
public void enjoy()
{
System.out.println("狗声.......");
}
}
class lady
{
String  name;
Animal  pet;
lady(String name,Animal pet)
{
this.name = name;
this.pet = pet;

}
public void enjoy()
{
pet.enjoy();
}
}
public class Testduotai
{
public static void main(String[] args)
{
Animal a = new Animal("a");
Cat c = new Cat("mimi","white");
Dog d = new Dog("bbeibei","black");
lady l1 = new lady("l1",a);
lady l2 = new lady("l2",c);
lady l3 = new lady("l3",d);
l1.enjoy();
l2.enjoy();
l3.enjoy();
} 
}