多态实例

package 多态;

//USB接口
//定义USB的规范，必须要完成接入和拔出的功能
//定义2个USB设备，鼠标，键盘

interface USB {
    void connect();//接入
    void unconnect();//拔出
}
class Mouse implements USB{

    private String name;

    public Mouse(String name){
        this.name = name;
    }
    
    //双击方法
    public void dbclick(){
        System.out.println("双击");
    }

    @Override
    public void unconnect() {
        System.out.println("成功的拔出了电脑");
    }
    @Override
    public void connect() {
        System.out.println("成功的接入了电脑");

    }
}
class Keyboard implements USB{
    private String name;

    public Keyboard(String name) {
        this.name = name;
    }
    
    
    //按键方法
    public void keyDown(){
        System.out.println("按键,写下了");
    }
    
    @Override
    public void connect() {
        System.out.println("成功的接入了电脑");

    }
    
    @Override
    public void unconnect() {
        System.out.println("成功的拔出了电脑");
    }
}
class Computer{
    
    //提供一个安装USB设备的入口
    public void install(USB usb){
        usb.connect();
        
        
        //usb可能是鼠标，也可能是键盘，一下作做判断
        if(usb instanceof Mouse){
            Mouse m = (Mouse) usb;
            m.dbclick();
        }else if(usb instanceof Keyboard){
            Keyboard k = (Keyboard)usb;
            k.keyDown();
        }

        usb.unconnect();
    }
}
class Test{


    public static void main(String[] args) {
        Computer c = new Computer();
        
        USB xiaomi = new Mouse("小米鼠标");
        c.install(xiaomi);

        USB luoji = new Keyboard("罗技");
        c.install(luoji);
    }
}