The simplest thing - why it doesn't work?????

Question

I develop a big application with lots of different panes containing all these controls...
I want the user to click a menu item and then the corresponding pane will appear, replacing completely in view any pane that appeard before that. I've tried everything - using JFrmae, JPane, JLayeredPane, rootpane, nothing seems to work perfectly .There's always a glitch and the previous pane somehow appears underneath under some circumstances.
I didn't find anything on that in the java tutorial or in the forums. I hope you guys could help me. Thanks in advance!

Answer 1

Thanks, that worked!
I now have all these different classes of panels that I can call from the frame class, but I can't call the frame class from any of the panes...
This is the error message that I get when I try to call a public method of the frame class from the pane class:
java.lang.NullPointerException
        at Pane1.workWithFrame(Pane1.java:76)
        at MyFrame$3.actionPerformed(MyFrame.java:137)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:17
86)
        at javax.swing.AbstractButton$ForwardActionEvents.actionPerformed(Abstra
ctButton.java:1839)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel
.java:420)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258
        at javax.swing.AbstractButton.doClick(AbstractButton.java:289)
        at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:1
113)
        at javax.swing.plaf.basic.BasicMenuItemUI$MouseInputHandler.mouseRelease
d(BasicMenuItemUI.java:943)
        at java.awt.Component.processMouseEvent(Component.java:5100)
        at java.awt.Component.processEvent(Component.java:4897)
        at java.awt.Container.processEvent(Container.java:1569)
        at java.awt.Component.dispatchEventImpl(Component.java:3615)
        at java.awt.Container.dispatchEventImpl(Container.java:1627)
        at java.awt.Component.dispatchEvent(Component.java:3477)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3483
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3198)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3128)
        at java.awt.Container.dispatchEventImpl(Container.java:1613)
        at java.awt.Window.dispatchEventImpl(Window.java:1606)
        at java.awt.Component.dispatchEvent(Component.java:3477)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:456)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchTh
read.java:201)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
ad.java:151)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:145)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:137)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)This is my frame class:
import java.util.*;
import java.util.Locale;
import java.util.ResourceBundle;
import java.util.ArrayList;
import java.util.Date;
import java.text.NumberFormat;
import java.text.DateFormat;
import java.io.File;
import java.io.RandomAccessFile;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.math.BigDecimal;
import java.awt.*;
import java.awt.event.*;
import java.awt.GridLayout;
import java.awt.Color;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowListener;
import java.awt.event.WindowEvent;
import java.awt.event.KeyEvent;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.rmi.PortableRemoteObject;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.*;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JMenuBar;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JOptionPane;
public class MyFrame extends JFrame{
        protected Dimension defaultSize = new Dimension(200, 200);
          public String frameString = "Santa";
          protected static MyFrame frame;
protected static Pane1 contentPane;
        JScrollPane scrollPane;
        public MyFrame(){
            setDefaultCloseOperation(DISPOSE_ON_CLOSE);
contentPane = new Pane1(frame);
     scrollPane = new JScrollPane(contentPane,
ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,
ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS
//Make it the content pane.
contentPane.setOpaque(true);
setContentPane(scrollPane);
            JMenu menu = new JMenu("Window");
            menu.setMnemonic(KeyEvent.VK_W);
            JMenuItem item = null;
            //close
            item = new JMenuItem("Close");
            item.setMnemonic(KeyEvent.VK_C);
            item.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent e) {
                    System.out.println("Close window");
                    MyFrame.this.setVisible(false);
                    MyFrame.this.dispose();
            menu.add(item);
            //new
            item = new JMenuItem("New");
            item.setMnemonic(KeyEvent.VK_N);
            item.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent e) {
                     setNewContentPane(contentPane.getPane2());
               contentPane.getPane2().addButtons(contentPane.getPane2().toolBar);
            menu.add(item);
            //quit
            item = new JMenuItem("Quit");
            item.setMnemonic(KeyEvent.VK_Q);
            item.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent e) {
setNewContentPane(contentPane);
contentPane.workWithFrame();
            menu.add(item);
        // Create the menu bar
        JMenuBar menuBar = new JMenuBar();
        // Create a menu
        JMenu servicesMenu = new JMenu("�������-�����");
        menuBar.add(servicesMenu);
       JMenu reportsMenu = new JMenu("�����");
        menuBar.add(reportsMenu);
       JMenu clientsMenu = new JMenu("������");
        menuBar.add(clientsMenu);
       JMenu jobsMenu = new JMenu("�����");
        menuBar.add(jobsMenu);
       JMenu candidatesMenu = new JMenu("�������");
        menuBar.add(candidatesMenu);
        menuBar.add(menu);
       // Create a menu item
        JMenuItem candidateInterviewSubpeneaMenuItem = new JMenuItem("����� �����");
       // item.addActionListener(actionListener);
        candidatesMenu.add(candidateInterviewSubpeneaMenuItem);
        JMenuItem interviewMenuItem = new JMenuItem("�����");
       // item.addActionListener(actionListener);
        candidatesMenu.add(interviewMenuItem);
        JMenuItem changeIntervieweeDetailsMenuItem = new JMenuItem("����� ���� �����");
       // item.addActionListener(actionListener);
        candidatesMenu.add(changeIntervieweeDetailsMenuItem);
        JMenuItem scanResumeMenuItem = new JMenuItem("����� ����� ����");
       // item.addActionListener(actionListener);
        candidatesMenu.add(scanResumeMenuItem);
        JMenuItem buildResumeMenuItem = new JMenuItem("����� ����� ���� �����");
       // item.addActionListener(actionListener);
        candidatesMenu.add(buildResumeMenuItem);
        JMenuItem updatePlacementMenuItem = new JMenuItem("����� ����");
       // item.addActionListener(actionListener);
        candidatesMenu.add(updatePlacementMenuItem);
        JMenuItem newClientMenuItem = new JMenuItem("���� ���");
       // item.addActionListener(actionListener);
        clientsMenu.add(newClientMenuItem);
        JMenuItem updateClientMenuItem = new JMenuItem("����� ���� ����");
       // item.addActionListener(actionListener);
        clientsMenu.add(updateClientMenuItem);
        JMenuItem newJobMenuItem = new JMenuItem("���� ����");
       // item.addActionListener(actionListener);
        jobsMenu.add(newJobMenuItem);
        JMenuItem updateJobMenuItem = new JMenuItem("����� ���� ����");
       // item.addActionListener(actionListener);
        jobsMenu.add(updateJobMenuItem);
        JMenuItem findMatchForJobMenuItem = new JMenuItem("����� ������� �����");
       // item.addActionListener(actionListener);
        jobsMenu.add(findMatchForJobMenuItem);
       JMenuItem interviewsReportMenuItem = new JMenuItem("��� �������");
       // item.addActionListener(actionListener);
        reportsMenu.add(interviewsReportMenuItem);
       JMenuItem candidatesReportMenuItem = new JMenuItem("��� �������");
       // item.addActionListener(actionListener);
        reportsMenu.add(candidatesReportMenuItem);
       JMenuItem clientsReportMenuItem = new JMenuItem("��� ������");
       // item.addActionListener(actionListener);
        reportsMenu.add(clientsReportMenuItem);
       JMenuItem jobsReportMenuItem = new JMenuItem("��� �����");
       // item.addActionListener(actionListener);
        reportsMenu.add(jobsReportMenuItem);
       JMenuItem phonebookReportMenuItem = new JMenuItem("��� �����");
       // item.addActionListener(actionListener);
        reportsMenu.add(phonebookReportMenuItem);
       JMenuItem placementReportMenuItem = new JMenuItem("��� �����");
       // item.addActionListener(actionListener);
        reportsMenu.add(placementReportMenuItem);
       JMenuItem statsReportMenuItem = new JMenuItem("��� ������");
       // item.addActionListener(actionListener);
        reportsMenu.add(statsReportMenuItem);
       JMenuItem evaluationReportMenuItem = new JMenuItem("��� �����");
       // item.addActionListener(actionListener);
        reportsMenu.add(evaluationReportMenuItem);
       JMenuItem rakazReportMenuItem = new JMenuItem("��� �����");
       // item.addActionListener(actionListener);
        reportsMenu.add(rakazReportMenuItem);
       JMenuItem hoursReportMenuItem = new JMenuItem("��� ����");
       // item.addActionListener(actionListener);
        reportsMenu.add(hoursReportMenuItem);
       JMenuItem callsReportMenuItem = new JMenuItem("��� �����");
       // item.addActionListener(actionListener);
        reportsMenu.add(callsReportMenuItem);
       JMenuItem settingsMenuItem = new JMenuItem("������");
       // item.addActionListener(actionListener);
        servicesMenu.add(settingsMenuItem);
       JMenuItem backupsMenuItem = new JMenuItem("�������");
       // item.addActionListener(actionListener);
        servicesMenu.add(backupsMenuItem);
       JMenuItem paperAdsMenuItem = new JMenuItem("������ ������");
       // item.addActionListener(actionListener);
        servicesMenu.add(paperAdsMenuItem);
       JMenuItem todoMsgsMenuItem = new JMenuItem("�����/������");
       // item.addActionListener(actionListener);
        servicesMenu.add(todoMsgsMenuItem);
       JMenuItem todoMsgsLogMenuItem = new JMenuItem("����");
       // item.addActionListener(actionListener);
        servicesMenu.add(todoMsgsLogMenuItem);
       JMenuItem chargeMenuItem = new JMenuItem("�����");
       // item.addActionListener(actionListener);
        servicesMenu.add(chargeMenuItem);
       JMenuItem marketingMenuItem = new JMenuItem("�����");
       // item.addActionListener(actionListener);
        servicesMenu.add(marketingMenuItem);
       JMenuItem reminderMenuItem = new JMenuItem("�������");
       // item.addActionListener(actionListener);
        servicesMenu.add(reminderMenuItem);
       JMenuItem phonebookMenuItem = new JMenuItem("�����");
       // item.addActionListener(actionListener);
        servicesMenu.add(phonebookMenuItem);
       JMenuItem statsMenuItem = new JMenuItem("������ ���������");
       // item.addActionListener(actionListener);
        servicesMenu.add(statsMenuItem);
       JMenuItem diallerMenuItem = new JMenuItem("�����");
       // item.addActionListener(actionListener);
        servicesMenu.add(diallerMenuItem);
       JMenuItem exitMenuItem = new JMenuItem("�����");
       // item.addActionListener(actionListener);
        servicesMenu.add(exitMenuItem);
        // Install the menu bar in the frame
            setJMenuBar(menuBar);
            setSize(defaultSize);
              pack();
              setVisible(true);
        public void displayPane2()
             System.out.println ("********************************************hello***********************************");       }
        public void setNewContentPane(JPanel pane)
                  scrollPane = new JScrollPane(pane,
ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,
ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS
//Make it the content pane.
pane.setOpaque(true);
setContentPane(scrollPane);
validate();
repaint();
        public static void main(String[] args)
              MyFrame frame = new MyFrame();
    }And this is my pane class:
import javax.swing.JToolBar;
import javax.swing.JButton;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.JScrollPane;
import javax.swing.JPanel;
import java.net.URL;
import java.awt.*;
import java.awt.event.*;
public class Pane1 extends JPanel
                         implements ActionListener {
    protected JTextArea textArea;
    protected String newline = "\n";
    static final private String PREVIOUS = "previous";
    static final private String UP = "up";
    static final private String NEXT = "next";
    private static MyFrame frame;
    private Pane2 pane2;
    public Pane1(MyFrame frame) {
        super(new BorderLayout());
          frame = frame;
//          frame.displayPane2();
          pane2 = new Pane2(frame);
        //Create the toolbar.
        JToolBar toolBar = new JToolBar();
        addButtons(toolBar);
        //Create the text area used for output.  Request
        //enough space for 5 rows and 30 columns.
        textArea = new JTextArea(5, 30);
        textArea.setEditable(false);
        JScrollPane scrollPane = new JScrollPane(textArea);
        //Lay out the main panel.
        setPreferredSize(new Dimension(150, 110));
        add(toolBar, BorderLayout.PAGE_START);
       add(scrollPane, BorderLayout.CENTER);
    protected void addButtons(JToolBar toolBar) {
        JButton button = null;
        //first button
        button = makeNavigationButton("Back24", PREVIOUS,
                                      "Back to previous something-or-other",
                                      "Previous");
        toolBar.add(button);
        //second button
        button = makeNavigationButton("Up24", UP,
                                      "Up to something-or-other",
                                      "Up");
        toolBar.add(button);
        //third button
        button = makeNavigationButton("Forward24", NEXT,
                                      "Forward to something-or-other",
                                      "Next");
        toolBar.add(button);
public Pane2 getPane2()
     return pane2;
public void workWithFrame()
        String fString = frame.frameString;
        System.out.println (fString);
    protected JButton makeNavigationButton(String imageName,
                                           String actionCommand,
                                           String toolTipText,
                                           String altText) {
        //Look for the image.
        String imgLocation = "toolbarButtonGraphics/navigation/"
                             + imageName
                             + ".gif";
        URL imageURL = Pane1.class.getResource(imgLocation);
        //Create and initialize the button.
        JButton button = new JButton();
        button.setActionCommand(actionCommand);
        button.setToolTipText(toolTipText);
        button.addActionListener(this);
        if (imageURL != null) {                      //image found
            button.setIcon(new ImageIcon(imageURL));
        } else {                                     //no image found
            button.setText(altText);
            System.err.println("Resource not found: "
                               + imgLocation);
        return button;
    public void actionPerformed(ActionEvent e) {
        String cmd = e.getActionCommand();
        String description = null;
        // Handle each button.
        if (PREVIOUS.equals(cmd)) { //first button clicked
            description = "taken you to the previous <something>.";
        } else if (UP.equals(cmd)) { // second button clicked
            description = "taken you up one level to <something>.";
        } else if (NEXT.equals(cmd)) { // third button clicked
            description = "taken you to the next <something>.";
  //      displayResult("If this were a real app, it would have "
  //                      + description);
//       frame.displayPane2();
    protected void displayResult(String actionDescription) {
        textArea.append(actionDescription + newline);
    public static void main(String[] args) {
        //Create and set up the content pane.
        Pane1 newContentPane = new Pane1();
        newContentPane.setOpaque(true);
}Why can I call the panes from the frame but not the other way around???
Thanks in advance!