Processing ActionListener in panel_class.

Question

Hi,
My application has:
1) JMenuBar
2) panel with cardlayout having 2 cards (screens)
on a contentpane.
The application is referred to as c1.
It is build with the use of seperate classes.
c2 = menubuilder
c3 = detailscreenbuilder
c4 = listscreenbuilder
All ActionListeners are created inside these classes.
So, C1 initializes and 'calls' C2, C3, C4 to build its screen.
When user selects a menu-item, the corresponding ActionListener is executed.
But how do I link this with an action in the applicationclass C1?
Example:
- User starts application
==> CardLayout shows default screen (c4)
==> JMenuBar is shown also
- User selects MenuItem:List.
==> an ActionListener, linked to the JMenuItem is triggered
This ActionListener is coded in the menubuilder (c2)
I would like to change the card_panel so that the detailscreen (c3) is shown.
This is done by executing: cardlayout.show("screen3");
Problem is... none of the objects used in the applicationclass are known to the menubuilder so how can I execute this?
Now I can

Answer 1

sorry, maybe the description is a bit difficult to understand without any code.
So, herewith you'll find the testcode (four classes)
Put them in a package called 'testscreenbuilder' and it should work.
The application starts with a menu and welcomescreen shown.
When selecting 'File - List', the 'ListPanel' should be displayed...
* Application
package testscreenbuilder;
import javax.swing.UIManager;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class myApplication
     extends JFrame {
     private Container c;
     private CardLayout cardlayout = new CardLayout();
     private JPanel pCards = new JPanel();
     boolean packFrame = false;
     private JPanel pNorth, pCenter, pSouth;
     private JLabel lNorth, lSouth, lCenter, lEast, lWest;
     // Variables
     private String titleScreen1, titleScreen2;
     private String gui = "J";
     private ActionListener al;
     //Construct the application
     public myApplication() {
          // Create View
          setTitle("myApplications");
          setSize(800, 550);
          c = getContentPane();
          c.setLayout(new BorderLayout());
          // add HomePanel
          pCards.setLayout(cardlayout);
          WelcomePanel cWelcome = new WelcomePanel(this, "welcome");
          pCards.add("welcome", cWelcome);
          ListPanel cList = new ListPanel();
          pCards.add("list", cList);
          cardlayout.show(pCards, "welcome");
          c.add(pCards, BorderLayout.CENTER);
          // add Menu
          Menu mMenu = new Menu();
          setJMenuBar(mMenu.getMenu());
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          setVisible(true);
     // MenuFrame1 frame = new MenuFrame1();
     //Validate frames that have preset sizes
     //Pack frames that have useful preferred size info, e.g. from their layout
     if (packFrame) {
          this.pack();
     else {
          this.validate();
     //Center the window
     Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
     Dimension frameSize = this.getSize();
     if (frameSize.height > screenSize.height) {
          frameSize.height = screenSize.height;
     if (frameSize.width > screenSize.width) {
          frameSize.width = screenSize.width;
     this.setLocation((screenSize.width - frameSize.width) / 2, (screenSize.height - frameSize.height) / 2);
     //Main method
     public static void main(String[] args) {
     try {
          UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
     catch(Exception e) {
          e.printStackTrace();
     new myApplication();
     class MenuHandlerList implements ActionListener{
          public void actionPerformed(ActionEvent e){
               cardlayout.show(pCards, "list");
* MenuBar
package testscreenbuilder;
import java.awt.event.*;
import javax.swing.*;
* @author pgo
public class Menu
     extends JFrame {
     private JMenuBar mMyMenu;
     // Menu
     private JMenu[] arMenu;
     private String arMenuText[] = {     
               "File", "Help"};
     // MenuItems
     private JMenuItem[] arMenuItem0;
     private String arMenuItem0Text[] = {
               "New", "List", "Exit"};
          private JMenuItem[] arMenuItem1;
     private String arMenuItem1Text[] = {
          "Help", "About..."};
public Menu() {
public JMenuBar getMenu() {
     if (arMenuText!=null)
          arMenu = new JMenu[arMenuText.length];
          // Menu 0 (File)
          if (arMenuItem0Text!=null)
               arMenu[0] = new JMenu(arMenuText[0]);
               arMenuItem0 = new JMenuItem[arMenuItem0Text.length];
               for (int si = 0;si<arMenuItem0Text.length;si++)
                    arMenuItem0[si] = new JMenuItem(arMenuItem0Text[si]);
                    switch(si)
                         case 0:     //New
                              arMenuItem0[si].addActionListener(new MenuHandler());
                              break;
                         case 1: //Properties
                              arMenuItem0[si].addActionListener(new MenuHandlerList());
                              break;
                         case 2: //Exit
                              arMenuItem0[si].addActionListener(new MenuHandlerExit());
                              break;
                         default:
                              arMenuItem0[si].addActionListener(new MenuHandler());
                              break;
                    arMenu[0].add(arMenuItem0[si]);
          // Menu 1 (Help)
          if (arMenuItem1Text!=null)
               arMenu[1] = new JMenu(arMenuText[1]);
               arMenuItem1 = new JMenuItem[arMenuItem1Text.length];
               for (int si = 0;si<arMenuItem1Text.length;si++)
                    arMenuItem1[si] = new JMenuItem(arMenuItem1Text[si]);
                    switch(si)
                         case 0: //Help
                              arMenuItem1[si].addActionListener(new MenuHandler());
                              break;
                         case 1: //About
                              arMenuItem1[si].addActionListener(new MenuHandlerAbout());
                              break;
                         default:
                              arMenuItem1[si].addActionListener(new MenuHandler());
                              break;
                    arMenu[1].add(arMenuItem1[si]);
     // Set MenuBar
     mMyMenu = new JMenuBar();
     if (arMenu != null)
          for (int i = 0;i<arMenu.length;i++){
               mMyMenu.add(arMenu);
     setJMenuBar(mMyMenu);
     return mMyMenu;
class MenuHandler implements ActionListener{
     public void actionPerformed(ActionEvent e){
     JMenuItem keuze = (JMenuItem)e.getSource();
     String tekst = keuze.getText();
     JOptionPane.showMessageDialog(null, "Function: '"+tekst+"' is under construction");
class MenuHandlerAbout implements ActionListener{
public void actionPerformed(ActionEvent e){
     JOptionPane.showMessageDialog(null, "My Application.\n\nVersion 1.0\nRelease Date June 2005");
class MenuHandlerExit implements ActionListener{
     public void actionPerformed(ActionEvent e){
     int response = JOptionPane.showConfirmDialog(null, "Are you sure that you wish to exit this application?", "Confirm Exit", JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE);
     if (response==0){
     System.exit(0);
class MenuHandlerList implements ActionListener{
     public void actionPerformed(ActionEvent e){
* Welcome Panel
package testscreenbuilder;
import java.awt.*;
import javax.swing.*;
* @author pgo
public class WelcomePanel
     extends JPanel {
     private JPanel pNorth, pCenter, pSouth, pEast, pWest;
     private JLabel lNorth, lSouth, lCenter, lEast, lWest;
     WelcomePanel(){
     WelcomePanel(myApplication application, String title)
     setLayout(new BorderLayout());
     pNorth = new JPanel();
     lNorth = new JLabel();
     lNorth.setText("Welcome Title");
     pNorth.add(lNorth);
     pEast = new JPanel();
     lEast = new JLabel("Welcome (East)");
     pEast.add(lEast);
     pCenter = new JPanel();
     lCenter = new JLabel("Welcome (Center)");
     pCenter.add(lCenter);
     pWest = new JPanel();
     lWest= new JLabel("Welcome (West)");
     pWest.add(lWest);
     pSouth = new JPanel();
     lSouth = new JLabel("Welcome South");
     pSouth.add(lSouth);
     add(pNorth, BorderLayout.NORTH);
     add(pEast, BorderLayout.EAST);
     add(pCenter, BorderLayout.CENTER);
     add(pWest, BorderLayout.WEST);
     add(pSouth, BorderLayout.SOUTH);
* ListPanel
package testscreenbuilder;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ListPanel
     extends JPanel {
     private String listTitle = new String("");
     private JLabel lblTitle;
     private JButton bListOK, bListNOK;
     private JPanel dpNorth, dpCenter, dpSouth;
     private JLabel dlNorth, dlSouth, dlCenter, dlEast, dlWest;
public ListPanel() {
     setLayout(new BorderLayout());
     dpNorth = new JPanel();
     dpNorth.setLayout(new FlowLayout());
     dpCenter = new JPanel();
     dpCenter.setLayout(new FlowLayout());
     dpSouth = new JPanel();
     dpSouth.setLayout(new FlowLayout());
     lblTitle = new JLabel("Properties");
     bListOK = new JButton("OK");
     bListOK.addActionListener(new ActionListenerOK());
     bListNOK = new JButton("Cancel");
     bListNOK.addActionListener(new ActionListenerNOK());
     dpNorth.add(lblTitle);
     dpSouth.add(bListOK);
     dpSouth.add(bListNOK);
     add(dpNorth, BorderLayout.NORTH);
     add(dpCenter, BorderLayout.CENTER);
     add(dpSouth, BorderLayout.SOUTH);
class ActionListenerOK implements ActionListener{
     public void actionPerformed(ActionEvent e){
class ActionListenerNOK implements ActionListener{
     public void actionPerformed(ActionEvent e){