APEX

I assume you are using the new sortable tables in Java 1.6+? I'm not too familiar with those yet, as I still code for 1.5, so I'll just throw out some ideas without examples.

Probably the easiest way I can think of is to just keep a handle on the sums row, and after each sort, move it back to the bottom.

Yes, I'm using java 6 se.
Please send me some examples if you can.

About handle. Seems like that's a good solution, but also it would be much better if there was some example of it. I don't know how to move the row back to the bottom after sort.
Thank you.

Why not just make sure your comparator recognises the last row and returns +1 regardless.

Sorry, I'm using default comparator in TableRowSorter.
Are you suggesting to use another comparator?

This crossed my mind, but wouldn't it move the sums row to the top when you sort by the same column again for a reverse order? Presumably, you would still want sums at the bottom.

How about a headless 2nd table whose only row contains the totals? Place him directly underneath the main table, with no gaps. If done correctly, he'll appear to be the last row of the original table.

Not only will he not move during sort, but also during scrolling (which I assume you'll also want).

This is not good, since if you change the column width, the bottom one will not change, of course you can set it's column width manually.

Just put a TableColumnModelListener on the TableColumnModel of the top table to keep the bottom table's column sizes in sync
Manual effort isn't needed with the above listener implemented properly. Honestly, I haven't tried this myself, but it should be do-able.

Reply #6 is definitely the way to go. Very little code is needed and the same ColumnModelListener can be used on ALL columns.

Since this whole problem interests me I have been experimenting with the problem. I have tried using the same column models but there seem to be side effects that I don't yet understand.

Me too. Here's my demo:

package gui;

import java.awt.*;

import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.*;

public class FixedTableRowDemo extends JFrame
{
  JTable dataTable;
  JTable summaryTable;
  
  public FixedTableRowDemo()
  {
    dataTable = new JTable(5, 5);
    dataTable.setPreferredScrollableViewportSize(
        dataTable.getPreferredSize());
    summaryTable = new JTable(1, 5);
    
    Container c = getContentPane(); 
    c.add(new JScrollPane(dataTable), BorderLayout.CENTER);
    c.add(summaryTable, BorderLayout.SOUTH);
    
    TableColumnModelListener tcmListener = new TableColumnModelListener()
    {
      public void columnMarginChanged(ChangeEvent e)
      {
        TableColumnModel dataModel = dataTable.getColumnModel();
        TableColumnModel summaryModel = summaryTable.getColumnModel();
        
        for (int i = 0; i < dataModel.getColumnCount(); i++)
        {
          summaryModel.getColumn(i).setPreferredWidth(
              dataModel.getColumn(i).getWidth());
        }
      }
      
      public void columnAdded(TableColumnModelEvent e){}
      public void columnMoved(TableColumnModelEvent e){}
      public void columnRemoved(TableColumnModelEvent e){}
      public void columnSelectionChanged(ListSelectionEvent e){}
    };
     
    dataTable.getColumnModel().addColumnModelListener(tcmListener);
//    summaryTable.setColumnModel(dataTable.getColumnModel());
    
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    pack();
    setLocationRelativeTo(null);
  }

  public static void main(String[] args)
  {
    JFrame frame = new FixedTableRowDemo();
    frame.setVisible(true);
  }
}

If I use the single ColumnModel approach, the resizing is very erratic. The listener seems to work well enough. Just comment/uncomment the 2 lines above the EXIT_ON_CLOSE line to experiment.

Side note: I wouldn't really use BorderLayout here since the table's columns aren't exactly in line with each other. It was just close enough for purposes of this demo. I'd probably whip out GBL.

I just tried to post my demo version which works pretty good BUT I can't get past the 5000 char limit without splitting into at least three bits. Bloody silly limitation.

These two posts are my example. It works pretty good but there is one significant niggle - when moving a column the 'total' table does not move smoothly but it does move. I look forward to 'camickr' reducing this to about 1 line.

Part A.

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Font;
import java.text.DecimalFormat;
import java.util.Comparator;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.TableColumnModelEvent;
import javax.swing.event.TableColumnModelListener;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.JTableHeader;
import javax.swing.table.TableColumnModel;
import javax.swing.table.TableModel;
import javax.swing.table.TableRowSorter;

public class Sabre20090331
{
    static private class TotalizingTableComponent extends JScrollPane
    {
        private TotalizingTableComponent(final TableModel tableModel)
        {
            final SecondaryTableModel secondaryTableModel = new SecondaryTableModel(tableModel);
            final JTable secondaryTable = new JTable(secondaryTableModel);
            for (int i = 1; i < secondaryTableModel.getColumnCount(); i++)
            {
                secondaryTable.getColumnModel().getColumn(i).setCellRenderer(new NumberCellRenderer());
            }
            secondaryTable.getColumnModel().getColumn(0).setCellRenderer(new TitleCellRenderer());
            final TableColumnModel secondaryTableColumnModel = secondaryTable.getColumnModel();
            secondaryTable.setRowSelectionAllowed(false);

            final JTable primaryTable = new JTable(tableModel);
            for (int i = 1; i < tableModel.getColumnCount(); i++)
            {
                primaryTable.getColumnModel().getColumn(i).setCellRenderer(new NumberCellRenderer());
            }
            final TableRowSorter<TableModel> sorter = new TableRowSorter<TableModel>(tableModel);
            final DoubleComparator doubleComparator = new DoubleComparator();
            for (int i = 1; i < tableModel.getColumnCount(); i++)
            {
                sorter.setComparator(i, doubleComparator);
            }
            primaryTable.setRowSorter(sorter);
            primaryTable.getColumnModel().addColumnModelListener(new TableColumnModelListener()
            {
                @Override
                public void columnAdded(TableColumnModelEvent e)
                {
                    // System.out.println("columnAdded()" + e);
                }

                @Override
                public void columnRemoved(TableColumnModelEvent e)
                {
                    // System.out.println("columnRemoved()" + e);
                }

                @Override
                public void columnMoved(TableColumnModelEvent e)
                {
                    //System.out.println("columnMoved()" + e);
                    secondaryTableColumnModel.moveColumn(e.getFromIndex(), e.getToIndex());
                }

                @Override
                public void columnMarginChanged(ChangeEvent e)
                {
                    //System.out.println("columnMarginChanged()" + e);
                    final TableColumnModel cm = (TableColumnModel) e.getSource();
                    for (int i = 0; i < cm.getColumnCount(); i++)
                    {
                        secondaryTableColumnModel.getColumn(i).setPreferredWidth(cm.getColumn(i).getWidth());
                    }
                }

                @Override
                public void columnSelectionChanged(ListSelectionEvent e)
                {
                    //System.out.println("columnSelectionChanged()" + e);
                }

            });

            final JTableHeader primaryHeader = primaryTable.getTableHeader();
            JPanel inner = new JPanel(new BorderLayout());
            this.setColumnHeaderView(primaryHeader);
            this.setViewportView(inner);
            inner.add(primaryTable, BorderLayout.NORTH);
            inner.add(secondaryTable, BorderLayout.CENTER);
        }

        public static void main(String[] args)
        {
            final JFrame frame = new JFrame("Totalizing JTable Example");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            final TableModel tableModel = new PrimaryTableModel();
            frame.setContentPane(new TotalizingTableComponent(tableModel));
            frame.pack();
            frame.setVisible(true);

        }

    }

}

Edited by: sabre150 on Apr 1, 2009 9:21 AM

Changed the layout of the inner panel so that the secondary table is now in the CENTER. This stops the secondary table becoming detached from the primary when one expands the frame beyond the prefferred size.

Part B.

class PrimaryTableModel extends AbstractTableModel
{
    @Override
    public Object getValueAt(int row, int col)
    {
        switch (col)
        {
            case 1:
                return new Double(row);
            case 2:
                return new Double(row * row);
            case 3:
                return new Double(row / (1.0 + row));
            default:
                return "Row " + row;
        }
    }

    @Override
    public int getColumnCount()
    {
        return columnNames.length;
    }

    @Override
    public int getRowCount()
    {
        return 30;
    }

    @Override
    public String getColumnName(int col)
    {
        return col < columnNames.length ? columnNames[col] : "";
    }

    private static final String[] columnNames =
    {
        "Title", "X", "Y", "Z"
    };
}

class SecondaryTableModel extends AbstractTableModel
{
    public SecondaryTableModel(TableModel primaryTableModel)
    {
        primaryTableModel_ = primaryTableModel;
    }

    @Override
    public boolean isCellEditable(int row, int col)
    {
        return false;
    }

    @Override
    public Object getValueAt(int row, int col)
    {
        if (col == 0)
            return "Total";
        else
        {
            double sum = 2;
            for (int i = 0; i < primaryTableModel_.getRowCount(); i++)
            {
                sum += (Double) primaryTableModel_.getValueAt(i, col);
            }
            return new Double(sum);
        }
    }

    @Override
    public int getColumnCount()
    {
        return primaryTableModel_.getColumnCount();
    }

    @Override
    public int getRowCount()
    {
        return 1;
    }

    @Override
    public String getColumnName(int col)
    {
        return primaryTableModel_.getColumnName(col);
    }

    private final TableModel primaryTableModel_;
}

class DoubleComparator implements Comparator<Double>
{
    public int compare(Double left, Double right)
    {
        return left.compareTo(right);
    }

}

class TitleCellRenderer extends DefaultTableCellRenderer
{
    @Override
    public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int col)
    {
        final Component comp = super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, col);
        if (table.convertColumnIndexToModel(col) == 0)
        {
            comp.setFont(comp.getFont().deriveFont(Font.BOLD));
            ((JLabel) comp).setHorizontalAlignment(JLabel.RIGHT);
        } else
        {
            comp.setFont(comp.getFont().deriveFont(Font.PLAIN));
            ((JLabel) comp).setHorizontalAlignment(JLabel.LEFT);
        }
        return comp;
    }

}

class NumberCellRenderer extends DefaultTableCellRenderer
{
    private final DecimalFormat formatter = new DecimalFormat("0.000");
    @Override
    public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int col)
    {
        boolean isNumber = value instanceof Number;
        if (isNumber)
        {
            value = formatter.format(value);
        }
        final Component comp = super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, col);
        ((JLabel) comp).setHorizontalAlignment(isNumber ? JLabel.RIGHT : JLabel.LEFT);

        return comp;
    }

}

Thank you very much. It works very good!
Except the one thing: when i'm moving column in the first table, it doesn't move in the second table.

Yes it does! As I said in my response, it is a niggle that the column moves but not smoothly. If one moves a column of the primary table then initially the secondary table column does not move but when one releases the primary column the secondary column jumps to the correct position.

Edited by: sabre150 on Apr 14, 2009 3:36 PM

I haven't actually tried this yet, what if you use a multi-column sort made up of a hidden column (in the model, not displayed) that has a 0 for data rows and a 1 for the total. Always sort ascending using the hidden column plus a secondary sort (ascending or descending) based on the column header the user clicks on. I guess you would need to listen for mouse clicks in the column header to force the two column sort.

Sounds like a good idea though I would use 'boolean' try and false rather than 0 or 1. An extension of what I suggested in reply #3. On probably would not need to listen to mouse clicks since the comparison functions could handle the dummy column. There might be a problem with ascending/descending but still worth looking at.