如何知道哪个线程先完成

Question

我创建了这两个线程（在其他情况下，我给了它们对我的问题不重要的属性）

我想知道我怎么知道哪个线程先完成

public class Race {

    public static void main(String[] args) {

        try {
            Thread th1 = new Thread(new Dog("Bubu",2));
            Thread th2 = new Thread(new Rabbit("Lepri",3));
            th1.start();
            th2.start();

        } catch (GaraException ex) {
            Logger.getLogger(Gara.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}

Answer 1

没有繁忙的循环或启动每个线程加入的线程：

        AtomicReference<Thread> first = new AtomicReference<>();

        Dog bubu = new Dog("Bubu",2);
        Thread th1 = new Thread(() -> {
            bubu.run();
            first.compareAndSet(null, Thread.currentThread());
        }, "Bubu");

        Rabbit lepri = new Rabbit("Lepri",3);
        Thread th2 = new Thread(() -> {
            lepri.run();
            first.compareAndSet(null, Thread.currentThread());
        }, "Lepri");

        th1.start();
        th2.start();
        th1.join();
        th2.join();

        System.err.println("First: "+first);

Answer 2

Java代码从上到下运行，如果您已经运行了该程序并成功运行，则意味着线程th1将在线程th2之前（从上到下）首先完成。