How to display one component on top of another in Java Swing?

Question

Java

There is a window:

class Window extends JFrame {

    int width = 1500;
    int height = 750;

    private JPanel mainPanel;
    private JPanel mapPanel;
    private JPanel pausePanel;

    Window() {

        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        setLayout(null);
        setSize(width + 5, height + 28);
        setResizable(false);
        setLocation((screenSize.width-getWidth())/2, (screenSize.height-getHeight())/2);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setVisible(true);

        mainPanel = new MainPanel();
        mapPanel = new MapPanel();
        pausePanel = new PausePanel();

        add(mainPanel);
        mainPanel.add(mapPanel);
        mainPanel.add(pausePanel);

        repaint();
    }

    void showPauseMenu () {
        pausePanel.setVisible(true);
    }

    void hidePauseMenu () {
        pausePanel.setVisible(false);
    }
}

In another piece of code, a call to showPauseMenu is registered when pressing Escape. What needs to be added to it so that the pausePanel is displayed on top of the mapPanel and not below it?

PS All panels - JPanel