试图等待所有线程完成

Question

由于某种原因，在for循环中进行第二次迭代之后，第二次启动thread1时，我得到一个java.lang.IllegalThreadStateException。我认为我根据这里的答案正确使用了加入How to wait for a number of threads to complete?。我的问题是为什么在第二次迭代我得到一个例外。

public void runThreads(){
        int numofTests;
        Scanner in = new Scanner(System.in);
        System.out.print("Enter the number of iterations to be completed:");
        numofTests = Integer.parseInt(in.nextLine());///Gets the number of tests from the user
        Agent agent = new Agent(numofTests);
        Smoker Pat = new Smoker ("paper", "Pam");
        Smoker Tom = new Smoker ("tobacco", "Tom");
        Smoker Matt = new Smoker ("matches", "Matt");
        Thread thread1 = new Thread(Pat);
        Thread thread2 = new Thread(Tom);
        Thread thread3 = new Thread(Matt);
        Thread thread4 = new Thread(agent);

        for (int i = 0; i < numofTests; i++){
        thread1.start();
        thread2.start();
        thread3.start();
        thread4.start();
        try {
            thread1.join();
            thread2.join();
            thread3.join();
            thread4.join();
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
        }

    }

Answer 1

您无法多次启动线程。如果要多次执行runnable，请重新创建一个新线程。