How to synchronize onMessage() of MessageListener
public void listAllJMS_Messages()
    {
        try {
            ObjectName objectName=new ObjectName("jboss.messaging.destination:name=DLQ,service=Queue");
            List ls = (List) server.invoke(objectName, "listAllMessages" , null, null);
            List<javax.jms.Message> messages=(List<javax.jms.Message>)server.invoke(objectName, "listAllMessages" , null, null);
            int count=0;
            for(javax.jms.Message msg : messages) {
                System.out.println((++count)+"t"+msg.getJMSMessageID());
               if(msg.getJMSType() != null && msg.getJMSType().equalsIgnoreCase("Text")) {
                TextMessage text = (TextMessage)msg;
                System.out.println(text.getText());
               }
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        // System.out.println((++count)+"t"+msg.getText());
    }