Java 多线程竞速模拟问题

Question

我有一个代表赛车的 class，在它里面我有一个方法每当汽车通过 1000 int 检查点时打印到控制台。

在运行重写中，我调用了该方法，并且它对我创建的每辆汽车的运行都不同，但我认为我弄错了，因为结果每次都在变化（它需要保持不变，因为有些车更快，所以我不认为这些车在不同的线程中移动。

public class RacingCar extends Thread{
private String model;
private int speed;
public RacingCar(){}
public RacingCar(String model, int speed){
    this.start();
    this.model = model;
    this.speed = speed;
}
public void go(){
    int trackLength=5000;
    int checkPointPassed=0;
    for(int i=0;i<trackLength;i+=speed){
        if(checkPointPassed*1000<i){
            checkPointPassed++;
            System.out.println(this.model+" has passed the "+checkPointPassed+"th check point");
        }
    }
}
@Override
public void run() {
    go();
    try {
        Thread.sleep(10);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}}

测试人员（主要）：

public class Tester {
public static void main(String[] args) {
    new RacingCar("Honda", 6);
    new RacingCar("Lamborghini", 100);
    new RacingCar("McLaren", 8);
}}

Answer 1

嗯，这里：

public RacingCar(String model, int speed){
    this.start();
    this.model = model;
    this.speed = speed;
}

您在对象完全创建之前使用 this.start()，这很糟糕。第二件事，你已经在线程运行之后分配参数（意味着非确定性行为）。

一般来说，您应该在构造函数之外创建对象并运行它。

Answer 2

您应该将睡眠移动到循环内，并在启动线程之前完全创建 RacingCars。

public class RacingCar extends Thread {
    private String model;
    private int speed;

    public RacingCar(String model, int speed) {
        this.model = model;
        this.speed = speed;
    }

    @Override
    public void run() {
        try {
            go();
        } catch(InterruptedException e) {
            e.printStackTrace();
        }
    }

    private void go() throws InterruptedException {
        int trackLength = 5000;
        int checkPointPassed = 0;
        for(int i = 0; i < trackLength; i += speed) {
            if(checkPointPassed * 1000 < i) {
                checkPointPassed++;
                System.out.println(this.model + " has passed the " + checkPointPassed + "th check point");
            }
            Thread.sleep(10);
        }
    }
}

public class Tester {
    public static void main(String[] args) {
        RacingCar honda = new RacingCar("Honda", 6);
        RacingCar lamborghini = new RacingCar("Lamborghini", 100);
        RacingCar mcLaren = new RacingCar("McLaren", 8);

        honda.start();
        lamborghini.start();
        mcLaren.start();
    }
}

（请注意，即使您这样做，也无法严格保证线程的调度顺序运行。）

Java 多线程竞速模拟问题

Java Multi-Thread racing simulation issue

java

eclipse

multithreading

thread-sleep

thread-synchronization