JDesktopPane won't hide it's frame

Question

I wanted to hide my JDesktopPane in a trigger of button. But this won't hide itself. I created a static void method that hides the frame and calling this in actionPerformed. Do I need to run another EDT to hide my frame? Any tips would appreciated.

import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.SwingUtilities;

public class JDesktoppane extends JFrame
{
JDesktopPane desktop;
JMenu menu;

public JDesktoppane()
{
   super("TITLE");
   int inset = 80;
   Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();

   setBounds(inset, inset,
           screenSize.width - inset*2,
           screenSize.height - inset*2);

    //Set up the GUI
   desktop = new JDesktopPane();
   //Setting JDesktopPane as Container
   setContentPane(desktop);
   setJMenuBar(createMenuBar());
   //Make dragging a little faster but perhaps uglier.
   desktop.setDragMode(JDesktopPane.OUTLINE_DRAG_MODE);
}

public JMenuBar createMenuBar()
{
    JMenuBar bar = new JMenuBar();

    menu = new JMenu("CLICK ME");

    JMenuItem item = new JMenuItem("CLICK ME AGAIN");
    item.addActionListener(listener);
    menu.add(item);

    bar.add(menu);


    return bar;
}

ActionListener listener = new ActionListener() 
{
    @Override
    public void actionPerformed(ActionEvent e) 
    {
        createFrame();
    }
};

public void createFrame()
{
    InternalFrame frame = new InternalFrame();
    frame.setVisible(true);
    desktop.add(frame);
}

public static void createAndShowGUI()
{
    JDesktoppane p = new JDesktoppane();
    p.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    p.setVisible(true);
}

public static void hideGUI()
{
    JDesktoppane p = new JDesktoppane();
    p.setVisible(false);
}

public static void main(String[] args) 
{
    SwingUtilities.invokeLater(new Runnable() {
        @Override
        public void run() {
            createAndShowGUI();
        }
    });
}

}

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JInternalFrame;
import javax.swing.JPanel;

public class InternalFrame extends JInternalFrame
{
public InternalFrame()
{
    addComponentsToPane(getContentPane());
    pack();
}

ActionListener listener = new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) 
    {
        JDesktoppane.hideGUI();
    }
};

private void addComponentsToPane(final Container pane)
{
    JPanel panel = new JPanel();
    panel.setLayout(new BorderLayout());
    JButton btn = new JButton("HIDE ME");
    btn.addActionListener(listener);
    panel.add(btn);
    pane.add(panel);
}
}

Answer 1

In hideGUI you are creating a new window and then hiding that:

public static void hideGUI()
{
    // creating a new window
    JDesktoppane p = new JDesktoppane();
    p.setVisible(false);
}

I think what you mean to do is somehow give the InternalFrame a reference to the original window that you create in createAndShowGUI.

You could do something like this:

public class InternalFrame extends JInternalFrame
{
    JDesktoppane parent;

    public InternalFrame(JDesktoppane parent)
    {
        this.parent = parent;

        addComponentsToPane(getContentPane());
        pack();
    }

    ActionListener listener = new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) 
        {
            // note
            parent.setVisible(false);
        }
    };
    ...
}

And:

public void createFrame()
{
    //                                      vvvv
    InternalFrame frame = new InternalFrame(this);
    frame.setVisible(true);
    desktop.add(frame);
}

It's a little strange though, for the internal pane to have a button which hides its parent. A more idiomatic way would be to have a JMenuBar or something like that with an option for it. (And do you have a plan to get the window back? Usually if you want to hide a window, you just minimize it.)