创建一个Cycle类，它具有子类Unicycle，Bicycle和Tricycle。演示每一个类型的实例都可以经由ride()方法向上转型为Cycle。

Thinking in Java 8.1 练习1 创建一个Cycle类，它具有子类Unicycle，Bicycle和Tricycle。演示每一个类型的实例都可以经由ride()方法向上转型为Cycle。

1，Cycle类

public class Cycle {
    public void play(){
        System.err.println("Cycle");
    }
}

2，Unicycle类

public class Unicycle extends Cycle{
    public void play(){
        System.err.println("Unicycle");
    }
}

3，Bicycle类

public class Bicycle extends Cycle {
    public void play(){
        System.err.println("Bicycle");
    }
}

4，Tricycle类

public class Tricycle extends Cycle {
    public void play(){
        System.err.println("Tricycle");
    }
}

5，Ride类

public class Ride {
    public static void ride(Cycle cycle){
        cycle.play();
    }

    public static void main(String[] args) {
        Unicycle unicycle = new Unicycle();
        Bicycle bicycle = new Bicycle();
        Tricycle tricycle = new Tricycle();
        ride(unicycle);
        ride(bicycle);
        ride(tricycle);

    }
}

来源：CSDN

作者：不懂技术的雷

链接：https://blog.csdn.net/qq_34703942/article/details/104817441