mulithread server with futureTask

[oll3i]

class SocketServer extends JFrame{
 
       JLabel label = new JLabel("Text received over socket:");
       JPanel panel;
       JTextArea progress = new JTextArea();
       ServerSocket server = null;
 
       Callable<String> reverseTask = new Callable<String>;
 
 
          public void listenSocket(){
            try{
              server = new ServerSocket(4444); 
            } catch (IOException e) {
              System.out.println("Could not listen on port 4444");
              System.exit(-1);
            }
            while(true){
 
                ClientWorker w;
                  try{
                      w = new ClientWorker(server.accept(), progress);
                        Thread t = new Thread(w);
                        t.start();
 
              } catch (IOException e) {
                System.out.println("Accept failed: 4444");
                System.exit(-1);
              }
            }
          }
 
 
 
 
 
 
 
 
       SocketServer(){ //Begin Constructor
           Font f = new Font("Dialog", Font.PLAIN, 16);
 
            progress.setFont(f);
            JPanel p = new JPanel();
            JButton b = new JButton("Start");
            b.addActionListener(new ActionListener() {
              public void actionPerformed(ActionEvent e) {
                ft = new FutureTaskCallback<String>(reverseTask);
                toReverse = progress.getText();
                exec.execute(ft);
              }
            });
            p.add(b);
            b = new JButton("Stop");
            b.addActionListener(new ActionListener() {
              public void actionPerformed(ActionEvent e) {
                if (ft != null) ft.cancel(true);
              }
            });
            p.add(b);
            Container cp = getContentPane();
            cp.setLayout(new BoxLayout(cp, BoxLayout.Y_AXIS));
 
            add(p);
            add(progress);
            setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            pack();
            setVisible(true);
       } //End Constructor
 
 
 
 
          ExecutorService exec = Executors.newSingleThreadExecutor();
              FutureTaskCallback<String> ft;          
 
 
              String toReverse;
 
 
 
 
 
 
 
 
 
 
 
 
      protected void finalize(){
//    Objects created in run method are finalized when 
//    program terminates and thread exits
         try{
            server.close();
        } catch (IOException e) {
            System.out.println("Could not close socket");
            System.exit(-1);
        }
      }
 
      public static void main(String[] args){
          SocketServer frame = new SocketServer();
        frame.setTitle("Server Program");
            WindowListener l = new WindowAdapter() {
                    public void windowClosing(WindowEvent e) {
                            System.exit(0);
                    }
            };
            frame.addWindowListener(l);
            frame.pack();
            frame.setVisible(true);
            frame.listenSocket();
      }
    }
 

why eclipse higlights this >>>. Callable<String> reverseTask = new Callable<String>;as an error

please help

[JosAH]

why eclipse higlights this >>>. Callable<String> reverseTask = new Callable<String>;as an error

please help

Because Callable is an interface, you can't instantiate it. I'm sure Eclipse tells
quite a bit more than just flagging it as an error; it also gives you the reason
why it is an error (which most of the time is the way to a solution).

kind regards,

Jos

[oll3i]

 while(true){
          ClientWorker w;
          FutureTask task = new FutureTask (new MyCallable ());
          ExecutorService es = Executors.newSingleThreadExecutor ();
          es.submit (task);
          try{
 
              int result = task.get();
              System.out.println ("Result from task.get () = " + result);
 
 
            w = new ClientWorker(server.accept(),  output);
            Thread t = new Thread(w);
            t.start();
          } catch (IOException e) {
            System.out.println("Accept failed: 4444");
            System.exit(-1);
          }
          es.shutdown (); 
        }
      }
 

now eclipse says cannot convert form object to int
here>>> int result = task.get();

[JosAH]

now eclipse says cannot convert form object to int
here>>> int result = task.get();

That's because FutureTask is a generic class, i.e. you have to specify the type
of what shall be returned by the FutureTask. You didn't specify anything so the
return type is Object. An Object can not be cast to an int as Eclipse correctly
noticed.

kind regards,

Jos

[oll3i]

public class MyCallable implements Callable
{String toReverse;
JTextArea output = new JTextArea();
ServerSocket server = null;
  public String call () throws java.io.IOException, InterruptedException {
 
      ClientWorker w = new ClientWorker(server.accept(),  output);
    Thread t = new Thread(w);
     t.start();
      ////Thread t = Thread.currentThread();
      if (toReverse == null || toReverse.trim().equals(""))
        throw new IllegalArgumentException("Set string to reverse");
      if (t.isInterrupted()) return null;
      char[] org = toReverse.toCharArray();
      StringBuffer out = new StringBuffer();
      if (t.isInterrupted()) return null;
      for (int i = org.length-1; i>=0; i--) {
        Thread.sleep(500);
        out.append(org[i]);
        if (t.isInterrupted()) return null;
        output.setText(out.toString());
        if (t.isInterrupted()) return null;
      }
      return out.toString();
    }
 

now i get java.lang.OutOfMemoryError: unable to create new native thread when i try to run a client i think it's in MyCallable

[oll3i]

help me please

[oll3i]

[code]
public void listenSocket(){

server = mycallable.getServer();
mycallable.setToReverse(textField.getText());
while(true){
///ClientWorker w;

FutureTaskCallback task = new FutureTaskCallback (mycallable);
ExecutorService es = Executors.newSingleThreadExecutor ();
es.submit (task);

es.shutdown ();
}
}[code]

this code causes Outofmemory error