Question

我需要为交通信号灯编写迭代方法。想法是红色是3分钟，然后它打开绿色，它是2分钟，然后它打开黄色，它是1分钟，然后它再次切换红色。迭代方法应该迭代状态机一分钟。我明白，它应该通过开关盒以某种方式完成，但我不知道如何....请帮助我。

public class TrafficLight
{
    private enum State {RED, YELLOW, GREEN};

    public void iterate()
    {
        switch(state)
        {
            case RED:   
            break;

            case GREEN: 
            break;

            case YELLOW:    
            break;
        }

    }

    public void setTimeForState(State state, int time)
    {

    }
}

对不起，系统剪了我的帖子，还有那个setTimeForState方法，其中更改红绿灯中特定颜色的等待时间。

Answer 1

您需要在类中定义变量状态：

class TrafficLight {
    enum State {
        RED, YELLOW, GREEN
    };

    State state = State.GREEN;

    public void iterate() throws InterruptedException {
        switch (this.state) {
        case RED:
            System.out.println("RED");
            Thread.sleep(1000);
            this.state = State.GREEN;
            break;

        case GREEN:
            System.out.println("GREEN");
            Thread.sleep(1000);
            this.state = State.YELLOW;
            break;

        case YELLOW:
            System.out.println("YELLOW");
            Thread.sleep(1000);
            this.state = State.RED;
            break;
        }

    }

并且在每种情况下等待一段时间将put状态转换为下一个值。

public static void main(final String[] args) throws InterruptedException {

    final TrafficLight a = new TrafficLight();
    while (true) {
        a.iterate();
    }
}

Answer 2

这里是路灯模拟器，它使用定时器和开关：

import java.util.Timer;
import java.util.TimerTask;

public class TrafficLight {

    static Timer timer =new Timer();

    private enum State {
        RED(3l), YELLOW(1l), GREEN(3l);
        Long time;

        State(Long time) {
            this.time = time * 1000  * 60;
        }

    };

    State state= State.RED;
    boolean direction = true;

    private static class ChangeState extends TimerTask {
        public ChangeState(TrafficLight lights) {

            this.lights = lights;
        }


        private final TrafficLight lights;


        @Override
        public void run() {

            switch (lights.state){
            case RED:
                lights.direction = false;
                lights.state = State.YELLOW;
                break;
            case YELLOW:
                if (lights.direction)
                    lights.state = State.RED;
                else
                    lights.state = State.GREEN;
                break;
            case GREEN:
                lights.direction = true;
                lights.state = State.YELLOW;
                break;
        }
        System.out.println(lights.state);
            timer.schedule(new ChangeState(lights),1000);// state.time);
        }
    };

    public void run(){
        System.out.println("state");
        timer.schedule(new ChangeState(this), state.time);
    }




    public static void main(String[] a) {
        (new TrafficLight()).run();
    }

}

枚举类型在java中，切换案例

2 个答案: