在多线程中:如何确定首先停止哪个线程

Question

编写一个名为RaceHorse的类来扩展Thread.每个RaceHorse都有一个名称和run()方法,显示名称5000次.编写一个实例化2个RaceHorse对象的Java应用程序.完成的最后一场RaceHorse是失败者.

这是个问题.我已经编写了两个类的代码两个运行线程以下是代码:

赛马

class RaceHorse extends Thread
{
    public String name;
    public RaceHorse(String name)
    {
        this.name = name;
    }
    public void run()
    {
        for(int i = 1 ; i <= 5000; i++)
        {
            System.out.println(i+"  "+name);
        }
        System.out.println(name+" finished.");
    }
}

跑步者

class Runner{
    public static void main(String args[])
    {
        RaceHorse obj = new RaceHorse("Lol");
        RaceHorse obj2 = new RaceHorse("BOL");
        Thread t = new Thread(obj);
        Thread t2 = new Thread(obj2);
        t.start();
        t2.start();
    }
}

现在我的问题是我无法找到首先完成哪个线程以及哪个秒,即哪个马获胜哪个失败.

Answer 1

首先:你的RaceHorse对象本身就是线程.你应该能够说出来obj.start();并且它也能正常工作.所以删除t并t2完全.

接下来,您需要一些方法来通知主线程有关获胜者的信息.

public void run()
{
    ... your loop stuff ...
    // this is how we're going to do the notification.
    Runner.done();
}

public class Runner
{
    private static RaceHorse winner = null;
    synchronized static void done()
    {
        // Threads calling this are going to be RaceHorse objects.
        // Now, if there isn't already a winner, this RaceHorse is the winner.
        if (winner == null) winner = (RaceHorse) Thread.currentThread();
    }

    public static void main(String[] args)
    {
         ... create the horses ...
         // start the horses running
         obj.start();
         obj2.start();

         // wait for them to finish
         obj.join();
         obj2.join();

         System.out.println(winner.name + " wins!");
    }
}

Answer 2

毫无疑问是一种更好的方法,但是一种方法可能是创建一个线程安全的类(例如'Trophy'),有一个方法'getTrohpy'只在第一​​次调用时返回true,并传递对一个实例的引用两个线程的奖杯.