实现一个双向适配器，使得猫可以学狗叫，狗可以学猫抓老鼠。

public class Client {
    public static void main(String[] args) {
        Adapter adapter = new Adapter();
        adapter.setCatAdapter(new ConcreteCat());
        Dog dog = adapter;
        dog.wang();

        adapter.setDogAdapter(new ConcreteDog());

        Cat cat = adapter;
        cat.catchMouse();

    }
}


public interface Dog {
    void wang();
}

public class ConcreteDog implements Dog {
    @Override
    public void wang() {
        System.out.println("狗汪汪叫");
    }
}


public interface Cat {
    void catchMouse();
}


public class ConcreteCat implements Cat {

    @Override
    public void catchMouse() {
        System.out.println("猫抓老鼠");
    }
}


public class Adapter implements Dog, Cat {
    private Dog dog;
    private Cat cat;

    public void setDogAdapter(Dog dog) {
        this.dog = dog;
    }

    public void setCatAdapter(Cat cat) {
        this.cat = cat;
    }

    @Override
    public void catchMouse() {
        System.out.print("猫学会了");
        dog.wang();
    }

    @Override
    public void wang() {
        System.out.print("狗学会了");
        cat.catchMouse();
    }
}