Changing Tabs in a TabbedPane

Question

I have created a JTabbedPane with four tabs each containing a panel with a JTable in a scrollpane. When i run i can only view first tab, clciing on the others show an empty tab. It's probably something simple! Another class adds this JPanel into a JFrame. Here is my code:
import javax.swing.JTable;
import javax.swing.JScrollPane;
import javax.swing.JTabbedPane;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JFrame;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class EReg extends JPanel {
public EReg() {
JTabbedPane tabbedPane = new JTabbedPane();
String[] changeOptions = { "standard modules", "resit modules", "other modules",
"view all changes" };
JButton button1 = new JButton("Get Details");
JComboBox changes = new JComboBox(changeOptions);
changes.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JComboBox cb = (JComboBox)e.getSource();
String viewType = (String)cb.getSelectedItem();}
JPanel labelPanel1 = new JPanel(new GridLayout (2, 1));
JLabel iDLabel1 = new JLabel("Student ID:");
JLabel nameLabel1 = new JLabel("Name of Student:");
labelPanel1.add(iDLabel1);
labelPanel1.add(nameLabel1);
JPanel textPanel1 = new JPanel(new GridLayout (2, 1));
JTextField studID1 = new JTextField();
JTextField name1 = new JTextField();
textPanel1.add(studID1);
textPanel1.add(name1);
JPanel topPanel = new JPanel();
topPanel.setLayout(new GridLayout(1,4));
topPanel.add(labelPanel1);
topPanel.add(textPanel1);
topPanel.add(changes);
topPanel.add(button1);
JTable viewTable = new JTable();
JPanel viewPanel = new JPanel(new BorderLayout());
viewPanel.add(topPanel, BorderLayout.NORTH);
viewPanel.add(viewTable, BorderLayout.CENTER);
tabbedPane.addTab("View", viewPanel);
tabbedPane.setSelectedIndex(0);
JPanel updatePanel = new UpdatePanel();
tabbedPane.addTab("Update", viewPanel );
JPanel approvePanel = new ApprovePanel();
tabbedPane.addTab("Approve", viewPanel);
JPanel courseDetPanel = new CourseDetPanel();
tabbedPane.addTab("Course Details", viewPanel);
setLayout(new GridLayout(1, 1));
add(tabbedPane);

Answer 1

Here is the full code with the tabs...each class compiles but when run, it doesnt show the panel, "vPanel", it just shows an empty panel instead. Thanx.
import javax.swing.JTable;
import javax.swing.JScrollPane;
import javax.swing.JTabbedPane;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JFrame;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class EReg extends JPanel {
public EReg() {
ViewPanel vPanel = new ViewPanel( );
JTabbedPane tabbedPane = new JTabbedPane();
tabbedPane.addTab("View",null, vPanel,"");
tabbedPane.setSelectedIndex(0);
setLayout(new GridLayout(1, 1));
add(tabbedPane);
public static void main(final String[] args) {
JFrame frame = new JFrame("e-Reg Logged in as " );
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {System.exit(0);}
frame.getContentPane().add(new EReg(),
BorderLayout.CENTER);
frame.setSize(800, 500);
frame.setVisible(true);
import javax.swing.JTable;
import javax.swing.JScrollPane;
import javax.swing.JTabbedPane;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class ViewPanel extends JPanel
{ JPanel viewPanel;
public JPanel ViewPanel()
{     String[] changeOptions = { "standard modules", "resit modules", "other modules",
"view all changes" };
JButton button1 = new JButton("Get Details");
JComboBox changes = new JComboBox(changeOptions);
changes.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JComboBox cb = (JComboBox)e.getSource();
String viewType = (String)cb.getSelectedItem();}
JPanel labelPanel1 = new JPanel(new GridLayout (2, 1));
JLabel iDLabel1 = new JLabel("Student ID:");
JLabel nameLabel1 = new JLabel("Name of Student:");
labelPanel1.add(iDLabel1);
labelPanel1.add(nameLabel1);
JPanel textPanel1 = new JPanel(new GridLayout (2, 1));
JTextField studID1 = new JTextField();
JTextField name1 = new JTextField();
textPanel1.add(studID1);
textPanel1.add(name1);
JPanel topPanel = new JPanel();
topPanel.setLayout(new GridLayout(1,4));
topPanel.add(labelPanel1);
topPanel.add(textPanel1);
topPanel.add(changes);
topPanel.add(button1);
JTable viewTable = new JTable();
viewPanel = new JPanel(new BorderLayout());
viewPanel.add(topPanel, BorderLayout.NORTH);
viewPanel.add(viewTable, BorderLayout.CENTER);
return viewPanel;
}