Question

如果是以下方式，我的代码工作正常。

Scanner input = new Scanner(System.in);
ExecutorService executor = Executors.newFixedThreadPool(2);
for (int i = 0; i < 3; i++) 
{
     Runnable worker = new ClassA();
     executor.execute(worker);
}

相反，我希望在while(true)循环中连续运行并在用户输入1时中断循环。我尝试了以下方式，但它无效。它没有连续运行，而是在这条线上停止（阻塞）int stop = input.nextInt();任何人都可以告诉我错误在哪里。是否是正确的做法，如果没有，请建议一个替代方案。我在A类中的代码连接到jms queue，并且应该连续读取队列中的消息。

Scanner input = new Scanner(System.in);
ExecutorService executor = Executors.newFixedThreadPool(2);
while(true)
{
     Runnable worker = new ClassA();
     executor.execute(worker);
     int stop = input.nextInt();
     if(stop == 1) {
            break;
     }
 }

编辑：以下是已编辑的代码。当scan.nextInt（）值输入1时，finished = true。当（！finished）循环中断时，其中的代码没有执行但仍然是我的Consumer类连续运行。

public class ScannerProblem {
   public static boolean finished = false;
   static class Listener implements Runnable {
      Scanner scanner = new Scanner(System.in);
      @Override
        public void run() {
            while (true) {
                System.out.println("scanning");
                if (scanner.nextInt() == 1) {
                    System.out.println("scanning finished");
                    finished = true;
                    return;
                } else {
                    System.out.println("scanned something strange");
                    try {
                        Thread.sleep(1500);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }

    static class Consumer implements Runnable {
        javax.jms.Connection jmsConnection = null;
        private static ProcessRequest processRequest = new ProcessRequest();
        @Override
        public void run() {
            ActiveMQConnection con = new ActiveMQConnection();
            jmsConnection = con.openTcpConnection();
            try {
                String json = null;
                Session session = jmsConnection.createSession(false,
                        Session.AUTO_ACKNOWLEDGE);
                Queue queue = session.createQueue("Upload_Queue");
                MessageConsumer consumer = session.createConsumer(queue);
                TextMessage message = (TextMessage) consumer.receive();
                System.out.println("Message #" + ": " + message.getText());
                json = message.getText();
                processRequest.upload(json);
                System.out.println("Thread ID: " +                 Thread.currentThread().getId());

            if (jmsConnection != null) {

                    jmsConnection.close();
            }

            Thread.sleep(5000);
        }
            catch(JMSException e) {
                e.printStackTrace();
            }
            catch(InterruptedException e){
                e.printStackTrace();
            }
            catch(Exception e) {
                e.printStackTrace();
            }
            }
    }



    public static void main(String[] args) {
        ExecutorService pool = Executors.newFixedThreadPool(2);
        pool.submit(new Listener());

        while (!finished) {
            System.out.println("finished::"+finished);
            pool.submit(new Consumer());
            try {
                Thread.sleep(4000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

Answer 1

int stop = input.nextInt（）是一个阻塞调用，所以它只执行一次ClassA runnable然后等待输入。

您需要将输入代码移动到另一个线程，因此它不会阻止ClassA的执行。

也许更好的选择是只有一次执行ClassA并在其中有另一个while（true）循环。

Scanner.nextInt（）阻止

1 个答案: