public  class MainFrame extends JFrame{
        JPanel contentPanel;

        public MainFrame(){}

       contentPanel = new JPanel();
       contentPanel.setLayout(new CardLayout());
       contentPanel.removeAll();
       contentPanel.add(new ContentPanel1());
       contentPanel.repaint();
       contentPanel.revalidate()

 }

public class WorkPlace extends JPanel implements key{
  public WorkPlace(){
           panel.setFocusable(true);
            panel.requestFocusInWindow();
      }
               @Override
                public void keyTyped(KeyEvent e) {}

                @Override
                public void keyReleased(KeyEvent e) {}

                @Override
                public void keyPressed(KeyEvent e) {
                    System.out.println("Pressed " + e.getKeyChar());
                }



  }