JTable in a JScrollPane (but not the usual problem :-)

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Joseph Knapka - 23 Aug 2003 07:29 GMT

Hi folks,

First post to this NG, so please be nice :-) The O'Reilly
"Swing" book, the API docs, and various FAQs haven't helped
me with this issue; perhaps someone here can.

I understand that in order to make my JTable behave properly
inside a JScrollPane, I have to set the auto-resize mode
to AUTO_RESIZE_OFF. That works fine, wrt column resizing
by the user. It does, however, cause a problem: when the
JTable is first displayed, all of the columns are at their
preferred widths, so there's a lot of empty space in the
JScrollPane in many cases, and the user is *forced* to
manually resize a bunch of columns just to get a readable
presentation.

The behavior I'd like to see is that when first displayed,
the JTable distributes the columns evenly across the
visible width of the JScrollPane. Then, when the user
subsequently resizes the columns, I want that to also
work as expected (showing the scrollbars when things get
too wide, etc). I tried initially adding the JTable
to the JScrollPane with auto-column-resizing enabled,
then subsequently disabling it, but that didn't
work (it acted as if autoresize was just disabled).

Is there a simple way to get the behavior I want? Is
there some well-known (to others) documentation that I
should have looked at before posting this? Pointers
to either would be greatly appreciated.

Many thanks,

-- Joe

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stdDisclaimer :: Lawsuit -> ()
stdDisclaimer = "These are my opinions etc., not TransCore's"
Joseph Knapka / Systems engineer / TransCore ITS Inc.
joseph.knapka@transcore.com / (915)549-5098

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Christian Kaufhold - 23 Aug 2003 12:14 GMT

Hello!

> I understand that in order to make my JTable behave properly
> inside a JScrollPane, I have to set the auto-resize mode
[quoted text clipped - 15 lines]
> then subsequently disabling it, but that didn't
> work (it acted as if autoresize was just disabled).

I am not sure about the notion of "first displayed".

Try this in JTable subclass:

private boolean firstDisplayed = true;

public boolean getScrollableTracksViewportWidth()
{
return firstDisplayed && getAutoResizeMode() == AUTO_RESIZE_OFF
? getPreferredSize().width < getParent().getWidth()
: super.getScrollableTracksViewportWidth();
}

public void doLayout()
{
super.doLayout();

if (firstDisplayed && getWidth() > 0)
{
firstDisplayed = false;

for (Enumeration i = getColumnModel().getColumns(); i.hasMoreElements();)
{
TableColumn c = (TableColumn)i.nextElement();

c.setPreferredWidth(c.getWidth());
}

revalidate();
}
}

getScrollableXXX makes the table initially become as wide as the viewport.
doLayout then updates the once-calculated preferred widths for that size.

I don't like it.

Maybe the real problem is that the JTable initially shows up at an impro-
per size (450 pixels wide) unrelated to its contents.
-> setPreferredScrollableViewportSize.

Christian

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JTable in a JScrollPane (but not the usual problem :-)

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