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How To Determine Position of JScrollPane in One JTable and ScrollSecond JTable

 
 
Haircuts Are Important
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      06-03-2013
How can I determine how much a JTable's JScrollPane has been moved,
and then scroll a second JTable based on that movement.

Thanks,
 
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Jim Gibson
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      06-03-2013
In article
<(E-Mail Removed)>,
Haircuts Are Important <(E-Mail Removed)> wrote:

> How can I determine how much a JTable's JScrollPane has been moved,
> and then scroll a second JTable based on that movement.


JScrollPane has two JScrollBar members: horizontalScrollBar and
verticalScrollBar. Use the getVerticalScrollBar() method of
JScrollPane, for example, to get the vertical scroll bar object.

Then use the getValue() method of JScrollBar to find out where the
scrollbar is positioned. You can define an AdjustmentListener object to
listen for scroll bar events. Then use the setValue() method to apply
the same offset to the other JScrollPane (assuming everything else
about the two JScrollPanes is equal).

--
Jim Gibson
 
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Lew
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      06-04-2013
Jim Gibson wrote:
> Haircuts Are Important wrote:
>> How can I determine how much a JTable's JScrollPane has been moved,
>> and then scroll a second JTable based on that movement.

>
> JScrollPane has two JScrollBar members: horizontalScrollBar and
> verticalScrollBar. Use the getVerticalScrollBar() method of
> JScrollPane, for example, to get the vertical scroll bar object.
>
> Then use the getValue() method of JScrollBar to find out where the
> scrollbar is positioned. You can define an AdjustmentListener object to
> listen for scroll bar events. Then use the setValue() method to apply
> the same offset to the other JScrollPane (assuming everything else
> about the two JScrollPanes is equal).


That is a beautifully succinct and informative post that I shall find
useful. Thank you.

OP (Original Poster): You can generalize from Jim's answer to coordinate
arbitrary widgets.

You can apply Jim's suggestion by using the Javadocs to find an equivalent
listener for the widget you want to track.

For example, some screen designs involve coordinated drop-down selections
and text or choices in other screen elements. For the drop-down widget you
use a JComboBox. Instead of an AdjustmentListener, you'd define an ActionListener and add it to the JComboBox with

http://docs.oracle.com/javase/7/docs...ActionListener)

You might update the contents of a prompt elsewhere on the screen with the
choice made in the combo box, using the listener to trigger the update.

Extending into another dimension, if you study the "model-view-controller"
(MVC) architecture of a good Swing screen, the same approach allows multiple
widgets to update based on a change to a data or object model. For example,
a stock-market ticker app could use a listener to a stock-price model
to update a visual chart of the price, at the same time as another part
of the display logic updates a moving average line on that chart using a
listener to get the latest data from the model.

--
Lew
 
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Haircuts Are Important
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      06-04-2013
On Jun 3, 7:56*pm, Jim Gibson <(E-Mail Removed)> wrote:
> In article
> <(E-Mail Removed)>,
> Haircuts Are Important <(E-Mail Removed)> wrote:
>
> > How can I determine how much a *JTable's JScrollPane has been moved,
> > and then scroll a second JTable based on that movement.

>
> JScrollPane has two JScrollBar members: horizontalScrollBar and
> verticalScrollBar. Use the getVerticalScrollBar() method of
> JScrollPane, for example, to get the vertical scroll bar object.
>
> Then use the getValue() method of JScrollBar to find out where the
> scrollbar is positioned. You can define an AdjustmentListener object to
> listen for scroll bar events. Then use the setValue() method to apply
> the same offset to the other JScrollPane (assuming everything else
> about the two JScrollPanes is equal).
>


I inserted the below code, but it did not work! Per
addAdjustmentListener, the two JScrollBars were always updated to the
same position, but the left JTable would not scroll with the right
JTable. The two tables have the same number of rows but differ in the
number of columns. What is wrong. I posted most of the project in a
recent posting.

JScrollPane leftScrollPane = new JScrollPane(fixedTable);
final JScrollBar leftVerticalScrollBar =
leftScrollPane.getVerticalScrollBar();

JScrollPane jScrollPane1 = new JScrollPane(scrollTable);
final JScrollBar rightVerticalScrollBar =
jScrollPane1.getVerticalScrollBar();

rightVerticalScrollBar.addAdjustmentListener(new AdjustmentListener(){
public void adjustmentValueChanged(AdjustmentEvent evt){
int rightPosition = rightVerticalScrollBar.getValue();
int lefttPosition = leftVerticalScrollBar.getValue();

if (rightPositon != leftPosition){
leftVerticalScrollBar.setValue(rightPosition);
}
}
});
 
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