使用带有Swing GUI类和侦听器的JFileChooser

This is my current menu :

这是我目前的菜单：

public class DrawPolygons
{
    public static void main (String[] args) throws FileNotFoundException
    {

        /**
         *   Menu - file reader option
         */

        JMenuBar menuBar;
        JMenu menu;
        JMenuItem menuItem;

        //  Create the menu bar.
        menuBar = new JMenuBar();

        //  Build the first menu.
        menu = new JMenu("File");
        menu.setMnemonic(KeyEvent.VK_F);
        menu.getAccessibleContext().setAccessibleDescription("I have items");
        menuBar.add(menu);

        //  a group of JMenuItems
        menuItem = new JMenuItem("Load",KeyEvent.VK_T);
        menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_1, ActionEvent.ALT_MASK));
        menuItem.getAccessibleContext().setAccessibleDescription("Load your old polygons");
        menu.add(menuItem);

        menuItem = new JMenuItem("Save",KeyEvent.VK_U);
        menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_2, ActionEvent.ALT_MASK));
        menuItem.getAccessibleContext().setAccessibleDescription("Save the contents of your polygons");
        menu.add(menuItem);

        // attaching the menu to the frame
        JFrame frame = new JFrame("Draw polygons");
        frame.setJMenuBar(menuBar);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setContentPane(new DrawingPanel());
        frame.pack();
        frame.setVisible(true);

    }

}
public