JTable lacks support for showing a footer with aggregated data for each column. Inspired by a suggested solution at Oracle/Suns bug database that looked promising, I started with the approach that the footer is painted by the border of the scrollpane.
Now at first I just want a 'proof of concept' and it seems I'm almost there, each column have a footer, widths are in sync. etc. So it seems to work pretty good except one thing, no text is painted! I expect the dummy values returned from getFooterValueAt painted on each "footer cell" but they're all blank, only the background (just for testing) is painted.
Why isn't any text painted? Is there something wrong with my position/size calculations in paintFooter?
import static java.awt.BorderLayout.CENTER;
import static java.awt.Color.BLUE;
import static java.awt.Color.CYAN;
import static java.awt.Color.GREEN;
import static java.awt.Color.LIGHT_GRAY;
import static java.awt.Color.MAGENTA;
import static java.awt.Color.ORANGE;
import static java.awt.Color.PINK;
import static java.awt.Color.RED;
import static java.awt.Color.WHITE;
import static java.awt.Color.YELLOW;
import static javax.swing.JTable.AUTO_RESIZE_OFF;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.Toolkit;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import javax.swing.CellRendererPane;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
import javax.swing.border.Border;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.TableColumnModelEvent;
import javax.swing.event.TableColumnModelListener;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableCellRenderer;
/**
* Demo application for JTable with footer.
*
* @author Martin Uhlén
*/
public class TableFooterBorderDemo extends JFrame
{
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
@Override
public void run()
{
new TableFooterBorderDemo().setVisible(true);
}
});
}
private TableFooterBorderDemo()
{
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
setLayout(new BorderLayout());
JTable table = createTable();
JScrollPane scroll = new JScrollPane(table);
add(scroll, CENTER);
TableFooter.install(scroll, table);
pack();
positionAtMiddleOfScreen();
}
private void positionAtMiddleOfScreen()
{
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
setLocation((int) ((screenSize.getWidth() / 2) - (getWidth() / 2)),
(int) ((screenSize.getHeight() / 2) - (getHeight() / 2)));
}
private JTable createTable()
{
Object[][] data = new Object[][]
{
{ "A", "*", "*", "*", "*", "*" },
{ "*", "B", "*", "*", "*", "*" },
{ "*", "*", "C", "*", "*", "*" },
{ "*", "*", "*", "D", "*", "*" },
{ "*", "*", "*", "*", "E", "*" },
{ "*", "*", "*", "*", "*", "F" }
};
Object[] columns = new Object[] { "A", "B", "C", "D", "E", "F" };
DefaultTableModel model = new DefaultTableModel(data, columns);
JTable table = new JTable(model);
table.setAutoResizeMode(AUTO_RESIZE_OFF);
return table;
}
/**
* A Border for JScrollPane that paints a footer for JTable.
*/
private static class TableFooter implements Border
{
private static final Color[] COLORS = {RED, GREEN, BLUE, YELLOW, PINK, CYAN, LIGHT_GRAY, MAGENTA, ORANGE, WHITE};
private final JScrollPane scroll;
private final JTable table;
private final CellRendererPane cellRendererPane;
TableFooter(JScrollPane scroll, JTable table)
{
this.scroll = scroll;
this.table = table;
cellRendererPane = new CellRendererPane();
}
public static TableFooter install(JScrollPane scroll, JTable table)
{
verify(scroll, table);
TableFooter footer = new TableFooter(scroll, table);
RepaintListener repainter = new RepaintListener(scroll);
scroll.getViewport().addChangeListener(repainter);
scroll.getHorizontalScrollBar().addAdjustmentListener(repainter);
table.getColumnModel().addColumnModelListener(repainter);
scroll.setViewportBorder(footer);
return footer;
}
private static void verify(JScrollPane scroll, JTable table)
{
if (scroll.getViewport().getView() != table)
{
throw new IllegalArgumentException("Given table must be inside given scroll pane");
}
}
/**
* @see javax.swing.border.Border#paintBorder(java.awt.Component, java.awt.Graphics, int, int, int, int)
*/
@Override
public void paintBorder(Component c, Graphics g, int x, int y, int width, int height)
{
System.out.println("x: " + x + ", y: " + y + ", width: " + width + ", height: " + height);
System.out.println("viewRect: " + scroll.getViewport().getViewRect());
paintFooter(g, x, y, width, height);
}
private void paintFooter(Graphics g, int x, int y, int width, int height)
{
Color oldColor = null;
Component cellRendererComponent = null;
int columnWidths = x - scroll.getViewport().getViewRect().x;
for (int column = 0; column < table.getColumnCount(); column++)
{
TableCellRenderer cellRenderer = table.getCellRenderer(0, column);
cellRendererComponent = cellRenderer.getTableCellRendererComponent(table, getFooterValueAt(column), false, false, 0, column);
if (oldColor == null)
{
oldColor = cellRendererComponent.getBackground();
}
int columnWidth = table.getColumnModel().getColumn(column).getWidth();
cellRendererComponent.setBackground(COLORS[column % COLORS.length]);
cellRendererPane.paintComponent(g, cellRendererComponent, scroll, columnWidths, y, columnWidth, height);
columnWidths += columnWidth;
}
if (cellRendererComponent != null)
{
cellRendererComponent.setBackground(oldColor);
}
}
private Object getFooterValueAt(int viewColumn)
{
return "Column " + viewColumn;
}
@Override
public Insets getBorderInsets(Component c)
{
return new Insets(0, 0, table.getRowHeight(), 0);
}
@Override
public boolean isBorderOpaque()
{
return true;
}
}
/**
* Repaints JScrollPane when needed.
*/
private static class RepaintListener implements ChangeListener, AdjustmentListener, TableColumnModelListener
{
private final JScrollPane scroll;
RepaintListener(JScrollPane scroll)
{
this.scroll = scroll;
}
@Override
public void columnAdded(TableColumnModelEvent e)
{
repaint();
}
@Override
public void columnRemoved(TableColumnModelEvent e)
{
repaint();
}
@Override
public void columnMoved(TableColumnModelEvent e)
{
repaint();
}
@Override
public void columnMarginChanged(ChangeEvent e)
{
repaint();
}
@Override
public void columnSelectionChanged(ListSelectionEvent e)
{
repaint();
}
@Override
public void adjustmentValueChanged(AdjustmentEvent e)
{
repaint();
}
@Override
public void stateChanged(ChangeEvent e)
{
repaint();
}
private void repaint()
{
scroll.repaint();
}
}
}
