绿灯亮30秒

class TrafficLights {

}

class RedLight extends TrafficLights {

}

class YellowLight extends TrafficLights {

}

class GreenLight extends TrafficLights {

}

public class Lights {
public static void main(String[] args) {
TrafficLights red = new RedLight();
lighten(red);
TrafficLights yellow = new YellowLight();
lighten(yellow);
TrafficLights green = new GreenLight();
lighten(green);
}

public static void lighten(TrafficLights light) {
    if(light instanceof RedLight) 
        System.out.println("红灯亮45秒");
    if(light instanceof YellowLight) 
        System.out.println("黄灯亮5秒");
    if(light instanceof GreenLight) 
        System.out.println("绿灯亮30秒");
}

}