I mentioned in the opening paragraph that this problem is a non-issue in JDK 6. Those of us still using JDK 5, though, need a solution!

-Ken

Your absolutely right – the grid lines don’t paint the entire viewport (one of the reasons I hid them!). Unfortunately, the BasicTableUI.paintGrid method is private, which makes fixing this issue just a little bit harder. Here is a method that you could stick in the table UI delegate I provided that would paint the missing grid lines:

private void paintEmptyRowGridLines(Graphics g) {
Graphics newGraphics = g.create();

// grab the y coordinate of the top of the first non-existent row (also
// can be thought of as the bottom of the last row).
int firstNonExistentRowY = getRowCount() * getRowHeight();

// only paint the region within the clipp bounds.
Rectangle clip = newGraphics.getClipBounds();

// paint the column grid dividers for the non-existent rows.
int x = 0;
for (int i = 0; i < getColumnCount(); i++) {
TableColumn column = getColumnModel().getColumn(i);
// increase the x position by the width of the current column.
x += column.getWidth();
newGraphics.setColor(table.getGridColor());
// draw the grid line (not sure what the -1 is for, but BasicTableUI
// also does it.
newGraphics.drawLine(x – 1, firstNonExistentRowY, x – 1, getHeight());
}

newGraphics.dispose();
}

Although this looks like an elegant solution to the “empty rows problem”, one area where it seems to fail is painting of any gridlines which might have been specified.

No, I understand those limitations. I mentioned setting the viewport’s background color only because it’s a quick-and-easy solution for some people’s needs. When I had needed to support DnD drops in the past, I had to use better fixes.

btw, if you want to see a different JViewPort hack, see http://bitguru.wordpress.com/2008/01/07/lazyviewport/

The technique you suggest works for the simple case, where you only want to change the background color. This wouldn’t work, though, if you wanted to draw row striping. I suppose you could install a custom JViewport on the JScrollpane, but it would have to have access to the JTable in order to draw the row striping.

Also note that if the JTable doesn’t fill the view, you can only right click directly over the table to bring up a context menu and only drop items (for a D&D operation) directly over the table.

-Ken

It doesn’t stretch the table to be any larger, but it makes it harder to tell.