JTable column header to span multiple columns

Question

Hi people. I've spent the last day trying to do this with no luck. Most of the links in the forum are old and don't exist any more and the ones that lead to some code end up not working on java 5 (I can compile and run but the result is not what I wanted)!
So my question is this, how do I have a column header that spans more than one column, which has individual column headers below it?
Thanks, Paul.
EDIT: I should point out that this is the place I've tried and although the screen shot of the first example looks exactly like what I want to do, it does not work as advertised. [http://www.crionics.com/products/opensource/faq/swing_ex/JTableExamples1.html]
Edited by: Boomah on 05-Nov-2008 15:08

Answer 1

Something like this?import java.awt.Dimension;
import java.awt.GridLayout;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.TableColumnModelEvent;
import javax.swing.event.TableColumnModelListener;
import javax.swing.table.*;
public class MultiSpanHeader {
   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         @Override
         public void run() {
            new MultiSpanHeader().makeUI();
   public void makeUI() {
      final JTable table = new JTable(5, 6);
      final JTableHeader header = table.getTableHeader();
      header.setReorderingAllowed(false);
      final TableColumnModel model = table.getColumnModel();
      Enumeration<TableColumn> enumColumns = model.getColumns();
      final List<TableColumn> columns = Collections.list(enumColumns);
      final JTable dummy = new JTable(0, 3);
      final JTableHeader dummyHeader = dummy.getTableHeader();
      dummyHeader.setReorderingAllowed(false);
      dummyHeader.setResizingAllowed(false);
      final TableColumnModel dummyModel = dummy.getColumnModel();
      Enumeration<TableColumn> enumDummyColumns = dummyModel.getColumns();
      final List<TableColumn> dummyColumns = Collections.list(enumDummyColumns);
      model.addColumnModelListener(new TableColumnModelListener() {
         @Override
         public void columnAdded(TableColumnModelEvent e) {
         @Override
         public void columnRemoved(TableColumnModelEvent e) {
         @Override
         public void columnMoved(TableColumnModelEvent e) {
         @Override
         public void columnMarginChanged(ChangeEvent e) {
            dummyColumns.get(0).setWidth(columns.get(0).getWidth());
            dummyColumns.get(1).setWidth(columns.get(1).getWidth() +
                  columns.get(2).getWidth());
            dummyColumns.get(2).setWidth(columns.get(3).getWidth() +
                  columns.get(4).getWidth() + columns.get(5).getWidth());
         @Override
         public void columnSelectionChanged(ListSelectionEvent e) {
      JScrollPane pane = new JScrollPane(table);
      pane.setPreferredSize(new Dimension(600, 200));
      JFrame frame = new JFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.add(pane);
      frame.pack();
      JPanel panel = new JPanel(new GridLayout(2, 1));
      panel.add(dummyHeader);
      panel.add(header);
      pane.getColumnHeader().setView(panel);
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
}Note: this is just presented as an idea, would need a lot of work to make it robust and flexible enough for practical use.
db