java利用接口实现USB，鼠标，键盘，电脑之间的关系

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代码：

USB.java public interface USB { // 开启USB public abstract void open(); // 关闭USB public abstract void close(); } Mouse.java public class Mouse implements USB { //重写接口的方法 @Override public void open() { } @Override public void close() { } // 点击鼠标 public void MouseClick(){ System.out.println("你现在点击了鼠标"); } } Keyboard.java public class Keyboard implements USB{ //重写接口的方法 @Override public void open() { } @Override public void close() { } // public void keyboardClick(){ System.out.println("你现在敲击的键盘"); } } Computer.java /*笔记本电脑的类*/ public class Computer { public void ComputerON(){ System.out.println("你电脑要开机了"); } public void ComputerOFF(){ System.out.println("你电脑要关机了"); } public void useDevice(USB usb){ usb.open(); // instanceof它的作用是测试它左边的对象是否是它右边的类的实例，返回 boolean 的数据类型。 if(usb instanceof Mouse){ // 强制类型转化 Mouse mouse = (Mouse) usb; mouse.MouseClick(); }else if(usb instanceof Keyboard){ // 强制类型转化 Keyboard keyboard = (Keyboard) usb; keyboard.keyboardClick(); } usb.close(); } } start.java //主函数 import java.util.Scanner; public class start { public static void main(String[] args) { Computer computer = new Computer(); // 电脑开机 computer.ComputerON(); Mouse mouse = new Mouse(); computer.useDevice(mouse); Keyboard keyboard = new Keyboard(); computer.useDevice(keyboard); //电脑关机 computer.ComputerOFF(); } }

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