java之如何定义USB接口

public interface USB {
    void turnOn();
    void turnOff();
}

//接口的实现类之鼠标
public class Mouse implements USB {
    public void turnOn(){
        System.out.println("鼠标启动了");
    }
    public void turnOff(){
        System.out.println("鼠标关闭了");
    }
}
//接口的实现类之键盘
public class KeyBoard implements USB{
    public void turnOn(){
        System.out.println("键盘启动了");
    }
    public void turnOff(){
        System.out.println("键盘关闭了");
    }
}
//接口的实现类之麦克风
public class Microphone implements USB{
    public void turnOn(){
        System.out.println("麦克风启动了");
    }
    public void turnOff(){
        System.out.println("麦克风关闭了");
    }
}

//计算机类
public class Computer {
    private USB[] usbArr = new USB[4];
    public void add(USB usb){
        for(int i = 0; i < usbArr.length;i++)
        {
            if(usbArr[i] == null)
            {
                usbArr[i] = usb;
                break;
            }
        }
    }
    public void powerOn() {
		for(int i=0;i<usbArr.length;i++) 
        {
			if(usbArr[i]!=null) 
            {
				usbArr[i].turnOn();
			}
		}
		System.out.println("电脑开机成功");
	}
	public void powerOff()
    {
		for(int i=0;i<usbArr.length;i++)
        {
			if(usbArr[i]!=null)
            {
				usbArr[i].turnOff();
			}
		}
		System.out.println("电脑关机成功");
	}
}

public class USBTest {
    public static void main(String[] args){
        Computer p = new Computer();
        p.add(new Mouse());
        p.add(new KeyBoard());
        p.add(new Microphone());
        p.powerOn();
        System.out.println("-----------------");
        p.powerOff();
    }
}

//使用一个接口实现一个标准,正常的开发中先写标准（接口），再写类
interface USB{
    public void insert();//插入
    public void setup();//安装驱动
}
//必须按着接口的标准使用电脑
class Computer{
    public void plugIn(USB usb){
        usb.insert();
        usb.setup();
    }
}
//鼠标
class  Mouse implements USB{
    public void insert(){
        System.out.println("鼠标插入");
    }
    public void setup(){
        System.out.println("鼠标安装驱动");
    }
}
//U盘
class UDisk implements USB{
    public void insert(){
        System.out.println("U盘插入");
    }
    public void setup(){
        System.out.println("U盘安装驱动");
    }
}
class InterfaceDemo{
    public static void main(String[] args) {
        Computer computer = new Computer();//实例化电脑的对象，调用其中的方法
        computer.plugIn(new Mouse());
        System.out.println("================");
        computer.plugIn(new UDisk());
    }
}