Question

I’m having problems passing some connection info to a runnable thread(using rabbitmq, but I don’t think this is specific to rabbitmq and can apply to anything). My goal is to have a few worker threads processing some work from a queue but I don’t want the overhead of opening and closing connections each time.

The code works without runnable(its actually stolen from the rabbitmq tutorials) but as soon as I implement a runnable passing a connection I get this error on doWork():
The method doWork(Channel, String) is undefined for the type Worker If I remove Channel from runnable and don’t send it then the program works fine but the connection information is not being passed. What can I do?

Here’s my code:

      //this is the standard stuff to start a connection
ConnectionFactory factory = new ConnectionFactory();
            factory.setHost("localhost");
            Connection connection = factory.newConnection();
            Channel channel = connection.createChannel();

        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

        channel.basicQos(1);

        QueueingConsumer consumer = new QueueingConsumer(channel);
        channel.basicConsume("task_queue", false, consumer);
      //end of standard stuff       

        while (true) {
          QueueingConsumer.Delivery delivery = consumer.nextDelivery();
          String message = new String(delivery.getBody());

          System.out.println(" [x] Received '" + message + "'");   
          doWork(channel, message); 
          System.out.println(" [x] Done" );

          channel.basicAck(delivery.getEnvelope().getDeliveryTag(), false);
        }
      }

then:

  public class doWork implements Runnable{

        protected Channel channel = null;
        protected String message   = null;

        public doWork(Channel channel, String message) {
            this.channel = channel;
            this.message   = message;
        }


        public void run() {

Answer 1

If you moved your code to a Runnable, this means you created a new class. If you want to invoke it, then you should have something like this

doWork work = new doWork(channel, message);
work.run();

But you probably want to move all that to an external Thread, which is done by:

Thread t = new Thread(new doWork(channel, message));
t.start();

Btw, classes should start with an upper-case letter, it makes the code much more readable.