private void onOK() {
   try {
     Map<String, String> data = new HashMap<String, String>();
     data.put("login", loginField.getText());
     data.put("password", passwordField.getText());
     String errorMsg = SocketManager.doAction(Constants.LOGIN_ACTION, data);
     if (errorMsg.equals("0")) {
       MainView mainView = new MainView();
       mainView.setVisible(true);
       dispose();
     } else {
       JOptionPane.showMessageDialog(this, errorMsg, "Error!", JOptionPane.ERROR_MESSAGE);
     }
   } catch (IOException e) {
     JOptionPane.showMessageDialog(this, e.getMessage(), "Error!", JOptionPane.ERROR_MESSAGE);
   }
 }