Question

I am trying to send request to server in every 2 seconds in a thread and check if there is something for me give it back to me….For getting value i have to use callable. I am not able to figure out how to run callable thread in every 2 seconds and get value back from it…here is my sample code of callable implementation…

public String call(){
    boolean done = true;
    String returnData = "";
    while(done){
        try {
            returnData = post.getAvailableChat();
            if(!returnData.equals("")){
                System.out.println("Value return by server is "+returnData);
                return returnData;
            }
            return null;
        } catch (IOException ex) {
            done = false;
            Logger.getLogger(GetChatThread.class.getName()).log(Level.SEVERE, null, ex);
        }

Now here is my main class code i know i did it wrong here in main class because my code will not go to next line after while loop….but please tell me how to do it

Callable<String> callable = new CallableImpl(2);                  

    ExecutorService executor = new ScheduledThreadPoolExecutor(1);   
    System.err.println("before future executor");                    
    Future<String> future;                                           

    try {                                                           
        while(chatLoop_veriable){                                    
            future = executor.submit(callable);                         
            String serverReply = future.get();                      
            if( serverReply != null){                               
                System.out.println("value returned by the server is "+serverReply);
                Thread.sleep(2*1000);                               
            }//End of if                                            
        }//End of loop                                              
    } catch (Exception e) {                                         

Answer 1

You rightly picked a ScheduledThreadPoolExecutor but you don’t take advantage of the methods it provides, in particular in your case: scheduleAtFixedRate instead of submit. You can then remove the sleep part as the executor will handle the scheduling for you.