接口的应用场景

1.创建一个接口USB

public interface USB {
    void open();
    void close();
}

2.创建一个类UPan实现接口USB

public class UPan implements USB{
    public void open(){
        System.out.println("upan open");
    }
    public void close(){
        System.out.println("upan close");
    }
}

3.使用Upan

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

        useUSB(new UPan());
    }

    public static void useUSB(USB u){
        u.open();
        u.close();
    }
}