Question

I have the following code. I m trying to access a queue and consume resources, well i dont know how many elements are in the queue and how many left, so i am doing while(true) but in this case, i cant close the connection which causes errors, later on, like the process doesnt die. even though i stopped it.

How can i find if there are more items in the queue then do the following ? i looked at ActiveMqQueueBrowser but it s internal so i cant really use it easily.

What would you do? What do u recommend?

    ConnectionFactory connectionFactory = new ActiveMQConnectionFactory(url);
    Connection connection = connectionFactory.createConnection();
    connection.start();

    Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);

    Destination destination = session.createQueue(subject);

    MessageConsumer consumer = session.createConsumer(destination);

    while(true){
            Message message = consumer.receive();

            if (message instanceof TextMessage) {
                TextMessage textMessage = (TextMessage) message;
                System.out.println("message from queue : '" + textMessage.getText() + "'");
            }
    }

   // unreachable code. compiler complains.
   // connection.close();

Answer 1

Sounds like you need to have another thread. How do you know when to be done listening? If its where the consumerQueue no longer has a value, try this:

while(true){
        Message message = consumer.receive(//some int timeout);
        if (message == null)
        {
            break;
        }

        if (message instanceof TextMessage) {
            TextMessage textMessage = (TextMessage) message;
            System.out.println("message from queue : '" + textMessage.getText() + "'");
        }
}

Otherwise you are right, the loop will never return and you won;t be able to close the connections correctly when the JVM comes down.