抽象类名作为形参和返回值

package com.daxing_01;

public class Cat {
    public void eat() {
        System.out.println("猫儿爱吃鱼！");
    }
}

package com.daxing_01;
//操作类
public class CatOperator {
    public void uesCat(Cat c){
        c.eat();
    }
}

package com.daxing_01;

public class CatDemo {
    public static void main(String[] args) {
        CatOperator co = new CatOperator();
        Cat c = new Cat();
        co.uesCat(c);
    }
}
运行结果：

猫儿爱吃鱼！

Process finished with exit code 0