抽象类名作为形参和返回值

package itheima_02;

public abstract class Animal {

    public  abstract  void eat();

}

package itheima_02;

public class AnimalOperator {

    public void useAnimal(Animal a){//Animal a = new Cat();
        a.eat();

}

   public Animal getAnimal(){
        Animal a = new Cat();
        return  a;

}

}

package itheima_02;

public class Cat extends Animal{

@Override

 public void eat() {
        System.out.println("猫吃鱼");

}

}

package itheima_02;

/*
测试类
*/

public class AnimalDemo {
    public static void main(String[] args) {

    //创建操作类对象,并调用方法

AnimalOperator ao = new AnimalOperator();
Animal a = new Cat();
ao.useAnimal(a);

Animal a2 = ao.getAnimal(); //new Cat()
a2.eat();
}

}