抽象类名作为形参和返回值

package com.daxing_02;

public abstract class Animal {
    public abstract void eat();
}

package com.daxing_02;

public class Operator {
    public void uesAnimal(Animal a) {
        a.eat();
    }

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

package com.daxing_02;

public class Cat extends Animal{
    @Override
    public void eat() {
        System.out.println("猫吃鱼🐟");
    }
}

package com.daxing_02;

public class Demo {
    public static void main(String[] args) {
        Operator ao = new Operator();
        Animal a = new Cat();
        ao.uesAnimal(a);

        Animal a2 = ao.getAnimal();
        a2.eat();
    }
}

运行结果：

猫吃鱼🐟
猫吃鱼🐟

Process finished with exit code 0