private class ButtonListener implements ActionListener
    {

        @Override
        public void actionPerformed(ActionEvent event)
        {
            String buttonText = event.getActionCommand();

            if (buttonText.equals("Lägg till"))
                addNumberToList();
            if (buttonText.equals("Ta bort"))
                removeCurrent();
            if (buttonText.equals("Load"))
                loadFromFile();
            if (buttonText.equals("Save"))
                writeToFile();

        }
    }