Java 接口和多态练习

我们鼠标和键盘实现USB接口，那么我们鼠标和键盘就变成了USB设备，这时候我们就可以把它放到笔记本电脑里面去用

 package com.biggw.day10.demo07; /**
  * @author gw
  * @date 2019/11/2 0002 下午 16:46
  */
 public class Computer {
     public void open() {
         System.out.println("打开电脑!");
     }     public void close() {
         System.out.println("关闭电脑!");
     }     public void useDevice(Usb usb) {
         if (usb instanceof KeyBorad) {
             KeyBorad keyBorad = (KeyBorad) usb;
             keyBorad.open();
             keyBorad.type();
             keyBorad.close();
         } else if (usb instanceof Mouse) {
             Mouse mouse = (Mouse) usb;
             mouse.open();
             mouse.click();
             mouse.close();
         }
     }
 }

Computer

 package com.biggw.day10.demo07; /**
  * @author gw
  * @date 2019/11/2 0002 下午 16:42
  */
 public interface Usb {
     public abstract void open();     public abstract void close();
 }

Usb 接口

 package com.biggw.day10.demo07; /**
  * @author gw
  * @date 2019/11/2 0002 下午 16:44
  */
 public class Mouse implements Usb {
     @Override
     public void open() {
         System.out.println("打开鼠标！");
     }     @Override
     public void close() {
         System.out.println("关闭鼠标!");
     }     public void click() {
         System.out.println("点击鼠标!");
     }
 }

Mouse Usb接口的实现类

 package com.biggw.day10.demo07; /**
  * @author gw
  * @date 2019/11/2 0002 下午 16:43
  */
 public class KeyBorad implements Usb {
     @Override
     public void open() {
         System.out.println("打开键盘!");
     }     @Override
     public void close() {
         System.out.println("关闭键盘!");
     }     public void type() {
         System.out.println("键盘输入文字!");
     }
 }

KeyBoard Usb接口的实现类

 package com.biggw.day10.demo07; /**
  * @author gw
  * @date 2019/11/2 0002 下午 16:52
  */
 public class Main {
     public static void main(String[] args) {
         Usb usb = new KeyBorad();
         Usb usb1 = new Mouse();         Computer computer = new Computer();
         computer.open();
         computer.useDevice(usb);
         computer.useDevice(usb1);
         computer.close();         /*点击鼠标!
         打开电脑!
         打开键盘!
         键盘输入文字!
         关闭键盘!
         打开鼠标！
         关闭鼠标!
         关闭电脑!*/
     }
 }

Main 方法入口