How do i check if an JInternalFrame is in a DesktopPane?

Question

Hey boys and girls :D
I have a JDesktopPane which controls my layout. I add JInternalFrames to the desktopPane everytime i open a new window. The problem is when i open a window, close it and then open it again, then i get the following error:
Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: illegal component position
So my thought is that i could check if the frame im trying to open, allready is in the desktopPane, then i could just set that frame visible and leave the desktop.add(frame) out.
The code im talking about is this and it doesnt work with the isVisible() i want to replace that with something which checks if the frame allready is in the desktopPane.
Isnt it the way to do it?
private void createItemMenuItemActionPerformed(java.awt.event.ActionEvent evt) {                                                  
        CreateItemGUI frame = control.getCreateItemGUI();
        if(frame.isVisible()){
            frame.setVisible(false);
        }else{
            frame.setVisible(true);
            desktopPane.add(frame);
    }  And the whole code:
* MainGUI.java
* Created on 13. april 2008, 11:46
package userclasses;
import javax.swing.JInternalFrame;
* @author  Jesper Johnsen
public class MainGUI extends javax.swing.JFrame {
    private Katrinelund control;
    /** Creates new form MainGUI */
    public MainGUI(Katrinelund control) {
        this.control = control;
        initComponents();
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {
        desktopPane = new javax.swing.JDesktopPane();
        jMenuBar1 = new javax.swing.JMenuBar();
        FileMenu = new javax.swing.JMenu();
        jMenuItem1 = new javax.swing.JMenuItem();
        jMenuItem2 = new javax.swing.JMenuItem();
        jMenuItem3 = new javax.swing.JMenuItem();
        itemControlMenu = new javax.swing.JMenu();
        searchItemMenuItem = new javax.swing.JMenuItem();
        createItemMenuItem = new javax.swing.JMenuItem();
        customerControlMenu = new javax.swing.JMenu();
        searchCustomerMenuItem = new javax.swing.JMenuItem();
        createCustomerMenuItem = new javax.swing.JMenuItem();
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Katrinelind administration");
        setBounds(new java.awt.Rectangle(0, 0, 2000, 800));
        desktopPane.setBackground(new java.awt.Color(255, 255, 255));
        FileMenu.setText("File");
        jMenuItem1.setText("?bn");
        FileMenu.add(jMenuItem1);
        jMenuItem2.setText("Luk");
        jMenuItem2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItem2ActionPerformed(evt);
        FileMenu.add(jMenuItem2);
        jMenuItem3.setText("Vis Frames");
        jMenuItem3.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                showFrames(evt);
        FileMenu.add(jMenuItem3);
        jMenuBar1.add(FileMenu);
        itemControlMenu.setText("Varestyring");
        searchItemMenuItem.setText("S?g vare(r)");
        searchItemMenuItem.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                searchItemMenuItemActionPerformed(evt);
        itemControlMenu.add(searchItemMenuItem);
        createItemMenuItem.setText("Tilf?j vare");
        createItemMenuItem.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                createItemMenuItemActionPerformed(evt);
        itemControlMenu.add(createItemMenuItem);
        jMenuBar1.add(itemControlMenu);
        customerControlMenu.setText("Kundestyring");
        searchCustomerMenuItem.setText("S?g kunde(r)");
        customerControlMenu.add(searchCustomerMenuItem);
        createCustomerMenuItem.setText("Tilf?j kunde");
        customerControlMenu.add(createCustomerMenuItem);
        jMenuBar1.add(customerControlMenu);
        setJMenuBar(jMenuBar1);
        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(desktopPane, javax.swing.GroupLayout.DEFAULT_SIZE, 1273, Short.MAX_VALUE)
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(desktopPane, javax.swing.GroupLayout.DEFAULT_SIZE, 778, Short.MAX_VALUE)
        pack();
    }// </editor-fold>
    private void searchItemMenuItemActionPerformed(java.awt.event.ActionEvent evt) {                                                  
        SearchGUI frame = control.getSearchGUI();
        frame.setVisible(true);
        desktopPane.add(frame);
    private void createItemMenuItemActionPerformed(java.awt.event.ActionEvent evt) {                                                  
        CreateItemGUI frame = control.getCreateItemGUI();
        if(frame.isVisible()){
            frame.setVisible(false);
        }else{
            frame.setVisible(true);
            desktopPane.add(frame);
    private void jMenuItem2ActionPerformed(java.awt.event.ActionEvent evt) {                                          
        quit();
    private void showFrames(java.awt.event.ActionEvent evt) {
        System.out.println(desktopPane.getComponents());
    public void addFrameToDesktop(JInternalFrame frame){
        frame.setVisible(true);
        desktopPane.add(frame);
    public void quit(){
        System.exit(0);
    // Variables declaration - do not modify
    private javax.swing.JMenu FileMenu;
    private javax.swing.JMenuItem createCustomerMenuItem;
    private javax.swing.JMenuItem createItemMenuItem;
    private javax.swing.JMenu customerControlMenu;
    private javax.swing.JDesktopPane desktopPane;
    private javax.swing.JMenu itemControlMenu;
    private javax.swing.JMenuBar jMenuBar1;
    private javax.swing.JMenuItem jMenuItem1;
    private javax.swing.JMenuItem jMenuItem2;
    private javax.swing.JMenuItem jMenuItem3;
    private javax.swing.JMenuItem searchCustomerMenuItem;
    private javax.swing.JMenuItem searchItemMenuItem;
    // End of variables declaration
}

Answer 1

In future, Swing related questions should be posted in the [Swing forum|http://forum.java.sun.com/forum.jspa?forumID=57]
Your code cannot be compiled and run as it has references to classes not part of the standard JDK. To get better help sooner, post a SSCCE that clearly demonstrates your problem.
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