JTabbedPane single event handling class.

Question

I have a list of proxyNames which are stored in a Vector.
These proxy names are then displayed as Tabs accordingly.
For every tab there is a specific action to be performed.
I want to write a single event handling class for handling all events.
What I have is this:
while(eNum.hasMoreElements()){
Object proxyName = eNum.nextElement();
tabbedPane.addTab(proxyName.toString(), null, null, "Proxy");
tabbedPane.addChangeListener(itemHandler);
panel4.add(tabbedPane2);
class ItemHandler implements ChangeListener{
public void stateChanged(ChangeEvent e){
for(int i=0; i < v.size(); i++){
// Perform action on choosing the concerned tab...
How do I have a single event listener?

Answer 1

Yikes! Is that a minimal program? When I am trying to do something new, or facing a problem that causes me to get stuck for more than an hour, I create a short program to solve just that problem. In time, you create a directory of test programs that's useful, and with practice, solving a problem in isolation is a faster (and generally better) way to go about things that doing it all in a larger application.
Any way, here is your code, with a change listener added in method makeSubpanel. If you don't want the listener called the very first time, add it at the end of this method. I also fixed some bugs in createProxyList.
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
import javax.swing.event.*;
public class TrialTabbed extends JPanel {
    // Will hold all file names read from the /config directory.
    private Vector v,v1;
    JTabbedPane tabbedPane,tabbedPane2;
    Object proxyName;
    public TrialTabbed(){
        tabbedPane = new JTabbedPane();
        // Instantiate the Vector.
        v1 = new Vector();
        Component panel1 = makeTextPanel("Blah");
        tabbedPane.addTab("Debug Mode", null, panel1, "Debug");
        Component panel2 = makeSubPanel();
        tabbedPane.addTab("Normal Mode", null, panel2, "Normal");
        // Add the tabbed pane to this panel.
        setLayout(new GridLayout(1, 1));
        add(tabbedPane);
    protected Component makeTextPanel(String text) {
        JPanel panel = new JPanel(false);
        JLabel filler = new JLabel(text);
        filler.setHorizontalAlignment(JLabel.CENTER);
        panel.setLayout(new GridLayout(1, 1));
        panel.add(filler);
        return panel;
    private Component makeSubPanel(){
        JPanel panel4 = new JPanel(false);
        panel4.setLayout(new GridLayout(1, 1));
        tabbedPane2 = new JTabbedPane();
        //new code - a change listener for pane2
        tabbedPane2.addChangeListener(new ChangeListener(){
            public void stateChanged(ChangeEvent e){
                int tab = tabbedPane2.getSelectedIndex();
                if (tab == -1)
                    System.out.println("no tab selected");
                else {
                    String filename = tabbedPane2.getTitleAt(tab);
                    File file = new File("..", filename); //brittle!
                    if (file.isDirectory())  {
                        String[] contents = file.list();
                        int size = contents == null ? 0 : contents.length;
                        System.out.println(filename + " contains " + size + " files");
                    } else
                        System.out.println(filename + " has length " + file.length());
        //end of new code
        ItemHandler itemHandler = new ItemHandler();
        v = createProxyList();
        // Enumerate thru the Vector and put them as tab names.
        Enumeration eNum = v.elements();
        while(eNum.hasMoreElements()){
            proxyName = eNum.nextElement();
            tabbedPane2.addTab(proxyName.toString(), null, null, "Proxy");
            panel4.add(tabbedPane2);
        return panel4;
    // Display the file names in this directory as tab Names.
    //new code: changed dirName to "..", fixed some obvious bugd
    private Vector createProxyList(){
        String dirName = "..";
        File file = new File(dirName);
        if(file.isDirectory()){
            String[] s = file.list();
            for(int i=0; i< s.length; i++){
                v1.addElement(s);
} // End for.
} // End of if.
return v1;
} // End createProxyList().
class ItemHandler implements ChangeListener{
public void stateChanged(ChangeEvent e){
System.out.println(v.size());
System.out.println("IN CHANGE LISETENER" + proxyName.toString());
} // End actionPerformed.
} // End Inner class ItemHandler.
public static void main(String[] args) {
JFrame frame = new JFrame("TabbedPaneDemo");
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {System.exit(0);}
frame.getContentPane().add(new TrialTabbed(),BorderLayout.CENTER);
frame.setSize(500, 425);
frame.setVisible(true);