Java bluetooth connection with jssc - troubles with key listeners

Question

I'm trying to make an app to connect computer with arduino via bluetooth. So far it was going well (I had simple buttons to sent 0 or 1 and connection was going smoothly), but when I added key listeners it stopped responding right after it connected. It's basically like this: - I click 'run', app opens, I can click buttons, I can push keys on keyboard and I get info that I'm not connected - click 'connect' - it's connected via bluetooth - I can still click on buttons (which now don't do anything) but as soon as I push a key I can't do anything - even click on an 'x' to close it. It appeared that the frame lost focus, so I set focusable on false on everything accept the frame. I'm out of ideas where the problem might be...

here's the code of connect button:

b1.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
    if(!connected){
        textArea.append("Connecting to the device on port "+ selectedCOM + "....\n");
                try {
                    serialPort = new SerialPort(selectedCOM);
                    textArea.append("Port opened: " + serialPort.openPort() + "\n");
                    textArea.append("Params set: " + serialPort.setParams(4800, 8, 1, 0) + "\n");

                    textArea.append("Connected succesfully!\n");
                    connected = true;

                } catch (SerialPortException e1) {
                    //e1.printStackTrace();
                    textArea.append("Error: "+e1.getExceptionType()+"\n");  
                }

            } else {
                textArea.append("You can't do that, you are already connected!\n");
            }
        }
    });

And a fragment of key listener (the rest if analogical):

addKeyListener(new KeyListener(){

        @Override
        public void keyPressed(KeyEvent e) {

            int key = e.getKeyCode();

            if (key == KeyEvent.VK_UP) {
                up.getModel().setPressed(true);

                if(connected){
                    try {
                        serialPort.writeInt(FORWARD);
                        System.out.println(FORWARD);
                    } catch (SerialPortException e1) {
                        textArea.append("Error: "+e1.getExceptionType()+"\n");
                        e1.printStackTrace();

                    }
                }
                else {
                    textArea.append("You are not connected.\n");
                }

FORWARD is defined as 1 :

private final int FORWARD = 1;

And also here is the whole main class: public class Communication{

private static void createAndShowGUI() {

    //Create and set up the window.
    Frame frame = new Frame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        

    //Display the window.
    frame.setFocusable(true);
    frame.setSize(new Dimension(600,600));
    frame.setLayout(new GridLayout());
    frame.setLocation(500, 250);
    frame.setResizable(false);
    frame.pack();
    frame.setVisible(true);

}

public static void main(String[] args)
{

    javax.swing.SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            createAndShowGUI();
        }
    });

}

}

The whole Frame class (which extends JFrame) has about 300 lines, so I didn't want to post it whole here. If it helps it's in here

EDIT: I changed key listeners to key bindings with swing workers, as suggested in comments, but it still doesn't responding. I think there may be some errors with connection but I have no idea how to resolve them...

Changes in the code:

forwardAction = new AbstractAction(){
        private static final long serialVersionUID = 1L;
        @Override
        public void actionPerformed(ActionEvent e) {
            SwingWorker<Void,Integer> worker = new SwingWorker<Void,Integer>(){

                @Override
                protected Void doInBackground() throws Exception {
                    goForward();
                    return null;
                }

            };
        worker.execute();
        }

    };
pane.getInputMap(IFW).put(KeyStroke.getKeyStroke("UP"), MOVE_FORWARD);
pane.getActionMap().put(MOVE_FORWARD,forwardAction);