JMenuBar to JFrame

Question

I have a menu bar in a JFrame JF when i click on the menubar item a new JFrame JF1 is created and is displayed , but when i clicked on the close button of JF1 , both JFrame are closed . When i click on close button of JF1 , i want only JF1 to be closed , not JF

JMenuBar menubar;
JMenu help;
JMenuItem about;

public GUI() {
    setLayout(new FlowLayout());

    menubar = new JMenuBar();
    add(menubar);

    help = new JMenu("Help");
    menubar.add(help);  
}`

Answer 1

a new JFrame JF1 is created and is displayed

Don't create a new JFrame an application should only have a single JFrame.

Instead create a JDialog . See: The Use of Multiple JFrames: Good or Bad Practice? for more information.

Also you don't add a JMenuBar to a JFrame using the add(...) method. See How to Use Menu Bars for the better way to do that.

Answer 2

I recomend you to use DesktopPane and JInternalFrame.

To the main Frame you make a change: contentPane (JPanel) will be JDesktopPane.

The JFrame that it's displayed whit the click will be a JInternalFrame.

In the actionListener of the JMenuItem, you will do this:

MyInternalFrame internalFrame = new MyInternalFrame();
internalFrame.show();
contentPane.add(internalFrame);

MyInternalFrame is the class of the Frame displayed (a class that extends JInternalFrame).

To close "internalFrame", just add a button to the layout whit the text "Quit" and in the actionListener of its you put "dispose()".

Try it and tell if it works ;)

--EDIT--- MAIN CLASS (The JFRAME)

public class Main extends JFrame {

private JDesktopPane contentPane;
private JMenuBar menuBar;
private JMenu mnExample;
private JMenuItem mntmAbout;

public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                Main frame = new Main();
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

public Main() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(20, 20, 800, 800);

    menuBar = new JMenuBar();
    setJMenuBar(menuBar);

    mnExample = new JMenu("Help");
    menuBar.add(mnExample);

    mntmAbout = new JMenuItem("About");
    mntmAbout.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            About frame = new About();
            frame.show();
            contentPane.add(frame);
        }
    });
    mnExample.add(mntmAbout);
    contentPane = new JDesktopPane();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    setContentPane(contentPane);
    contentPane.setLayout(null);
}
}

ABOUT CLASS (The JINTERNALFRAME)

public class About extends JInternalFrame {

public About() {
    setBounds(100, 100, 544, 372);

    JLabel lblSomeText = new JLabel("Some Text");
    getContentPane().add(lblSomeText, BorderLayout.CENTER);

    JButton btnClose = new JButton("Close");
    btnClose.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            dispose();
        }
    });
    getContentPane().add(btnClose, BorderLayout.SOUTH);

}

}