Assigning an ActionListener to an inherited JButton

Question

Dear all,
I have a base JPanel class with a button, a border and not much else. This class is extended by 2 other classes in my application.
I needed a means of associating an action with the button in my application's main class, so I added a static method addButtonListener to the base class, assuming that once I invoked this, the button would be 'activated' in all the panels inheriting from my base class. addButtonListener() simply invokes the button's addActionListener() method.
Unfortunately this doesn't work, the ActionListener only gets linked to the button in one of the child classes (the first one that's instantiated).
What's going on? The code for the base class is below...
import java.awt.BorderLayout;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.border.CompoundBorder;
import javax.swing.border.EmptyBorder;
import javax.swing.border.EtchedBorder;
import javax.swing.border.TitledBorder;
public class LoadVolPanel extends JPanel {
     protected JPanel buttonPanel;
     protected static JButton loadButton;
     public static void addButtonListener(ActionListener a) {
          loadButton.addActionListener(a);
     public LoadVolPanel(String title) {
          super();
          setBorder(new CompoundBorder(
                    new TitledBorder(new EtchedBorder(), title), new EmptyBorder(3,
                              5, 3, 5)));
          loadButton = new JButton("Load surfaces");
          loadButton.setMnemonic('L');
          buttonPanel = new JPanel();
          buttonPanel.add(loadButton);
          setLayout(new BorderLayout());
          add(buttonPanel, BorderLayout.SOUTH);
}

Answer 1

I apologise for the amount of the code I've posted but it does compile, and will hopefully show you what I'm trying to do.
I would like:
- the Load button to appear at the bottom of each tab in the parent JTabbedPane;
- the Load button perform the same action in all panes;
- to be able to assign an action to the Load button from the main class.
Cheers!
import javax.swing.*;
import javax.swing.border.*;
import java.awt.*;
import java.awt.event.*;
public class TestClass {
     public class LoadVolPanel extends JPanel {
          protected JPanel buttonPanel;
          protected JButton loadButton;
          public void AddButtonListener(ActionListener a) {
               loadButton.addActionListener(a);
          public LoadVolPanel(String title) {
               super();
               setBorder(new CompoundBorder(new TitledBorder(new EtchedBorder(),
                         title), new EmptyBorder(3, 5, 3, 5)));
               loadButton = new JButton("Load surfaces");
               loadButton.setMnemonic('L');
               buttonPanel = new JPanel();
               buttonPanel.add(loadButton);
               setLayout(new BorderLayout());
               add(buttonPanel, BorderLayout.SOUTH);
     public class LogPanel extends LoadVolPanel {
          public LogPanel() {
               super("Log");
               JTextArea ta = new JTextArea();
               ta.setLineWrap(true);
               ta.setWrapStyleWord(true);
               ta.setEditable(false);
               ta.append("The Load Surfaces button below kicks off\n");
               ta.append("a shell script on a unix box\n");
               ta.append("Output from the script appears here.\n");
               JScrollPane scroll = new JScrollPane();
               scroll.getViewport().add(ta);
               add(scroll, BorderLayout.CENTER);
     public class LoadPanel extends LoadVolPanel {
          protected JList securitiesList;
          public final int VISIBLE_ROWS = 12;
          private JTabbedPane tabbedPane;
          private CheckListCell[] volCodes = { new CheckListCell("AMP"),
                    new CheckListCell("ALN"), new CheckListCell("ANN"),
                    new CheckListCell("ANZ"), new CheckListCell("ASX"),
                    new CheckListCell("AXA"), new CheckListCell("BNB"),
                    new CheckListCell("BIL"), new CheckListCell("BSL"),
                    new CheckListCell("CBA"), new CheckListCell("CML"),
                    new CheckListCell("CSR"), new CheckListCell("DJS"),
                    new CheckListCell("FOA"), new CheckListCell("FXJ"),
                    new CheckListCell("GNS"), new CheckListCell("GPT"),
                    new CheckListCell("IAG"), new CheckListCell("JHX"),
                    new CheckListCell("LEI"), new CheckListCell("MAP"),
                    new CheckListCell("MBL"), new CheckListCell("MIG"),
                    new CheckListCell("NAB"), new CheckListCell("NWS"),
                    new CheckListCell("NWSLV"), new CheckListCell("ORG"),
                    new CheckListCell("OST"), new CheckListCell("PBG"),
                    new CheckListCell("PBL"), new CheckListCell("PMN"),
                    new CheckListCell("QAN"), new CheckListCell("RIN"),
                    new CheckListCell("RIO"), new CheckListCell("SEV"),
                    new CheckListCell("SGB"), new CheckListCell("SHL"),
                    new CheckListCell("SSX"), new CheckListCell("STO"),
                    new CheckListCell("TAH"), new CheckListCell("TCL"),
                    new CheckListCell("TLS"), new CheckListCell("VBA"),
                    new CheckListCell("WBC"), new CheckListCell("WDC"),
                    new CheckListCell("WMR"), new CheckListCell("WOW"),
                    new CheckListCell("WPL"), new CheckListCell("WSF"),
                    new CheckListCell("ZFX"), new CheckListCell("CCL"), };
          public LoadPanel() {
               super("Codes");
               securitiesList = new JList(volCodes);
               CheckListCellRenderer renderer = new CheckListCellRenderer();
               securitiesList.setCellRenderer(renderer);
               securitiesList
                         .setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
               securitiesList.setLayoutOrientation(JList.VERTICAL_WRAP);
               securitiesList.setVisibleRowCount(VISIBLE_ROWS);
               JScrollPane ps = new JScrollPane();
               ps.getViewport().add(securitiesList);
               JButton refreshButton = new JButton("Refresh Securities List");
               buttonPanel.add(refreshButton);
               add(ps, BorderLayout.CENTER);
     public final class CheckListCell {
          private String name;
          private boolean selected;
          public CheckListCell(String name) {
               this.name = name;
               selected = false;
          public String getName() {
               return this.name;
          public void setSelected(boolean selected) {
               this.selected = selected;
          public void invertSelected() {
               selected = !selected;
          public boolean isSelected() {
               return selected;
          public String toString() {
               return name;
     public final class CheckListener implements MouseListener, KeyListener {
          private LoadPanel parent;
          private JList securitiesList;
          public CheckListener(LoadPanel parentPanel) {
               parent = parentPanel;
               securitiesList = parentPanel.securitiesList;
          public void mouseClicked(MouseEvent e) {
               int index = securitiesList.locationToIndex(e.getPoint());
               if (index == securitiesList.getSelectedIndex())
                    doCheck();
          public void mousePressed(MouseEvent e) {
          public void mouseReleased(MouseEvent e) {
          public void mouseEntered(MouseEvent e) {
          public void mouseExited(MouseEvent e) {
          public void keyPressed(KeyEvent e) {
               if (e.getKeyChar() == ' ')
                    doCheck();
          public void keyTyped(KeyEvent e) {
          public void keyReleased(KeyEvent e) {
          private void doCheck() {
               int index = securitiesList.getSelectedIndex();
               if (index >= 0) {
                    CheckListCell cell = (CheckListCell) securitiesList.getModel()
                              .getElementAt(index);
                    cell.invertSelected();
                    securitiesList.repaint();
     public class CheckListCellRenderer extends JCheckBox implements
               ListCellRenderer {
          private Border noFocusBorder = new EmptyBorder(1, 1, 1, 1);
          public CheckListCellRenderer() {
               setOpaque(true);
               setBorder(noFocusBorder);
          public Component getListCellRendererComponent(JList list, Object value,
                    int index, boolean isSelected, boolean cellHasFocus) {
               if (value != null)
                    setText(value.toString());
               setBackground(isSelected ? list.getSelectionBackground() : list
                         .getBackground());
               setForeground(isSelected ? list.getSelectionForeground() : list
                         .getForeground());
               CheckListCell data = (CheckListCell) value;
               setSelected(data.isSelected());
               setFont(list.getFont());
               setBorder((cellHasFocus) ? UIManager
                         .getBorder("List.focusCellHighlightBorder") : noFocusBorder);
               return this;
     public static void main(String argv[]) {
          JFrame frame = new JFrame("Load Volatility");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.setSize(370, 330);
          TestClass myTest = new TestClass();
          JPanel logPanel = myTest.new LogPanel();
          LoadPanel loadPanel = myTest.new LoadPanel();
          JTabbedPane jtp = new JTabbedPane();
          jtp.addTab("Load Volatility", loadPanel);
          jtp.addTab("Log", logPanel);
          frame.getContentPane().add(jtp);
          frame.pack();
          frame.show();
}