Solved

JTable repaint()

Posted on 2002-04-08
16
1,633 Views
Last Modified: 2012-08-14
When I call the repaint() method of JTable, the row selection is vanished. I would like to restore the selection status.
Holding the selected rows indices is a bad idea, since their order might be changed after repainting (if the table is sorted, for example).
Any idea?
0
Comment
Question by:s_lavie
  • 6
  • 6
  • 4
16 Comments
 
LVL 16

Accepted Solution

by:
heyhey_ earned 50 total points
Comment Utility
> since their order might be changed after repainting

WRONG. you never need to call repaint() - all you have to do is make changes inside your models (TableModel, SelectionModel) and fire appropriate events. TableUI will handle these events and repaints itself if needed.
0
 
LVL 92

Expert Comment

by:objects
Comment Utility
> When I call the repaint() method of JTable,
> the row selection is vanished.

Then the row must no longer be selected.
0
 
LVL 2

Author Comment

by:s_lavie
Comment Utility
Okay, no more calling to repaint() and the selection is not vanished, but the wrong line is now selected, i.e. for example I have a table like this:

0     a
1     b
2     c
3     d

Now, suppose row index 1 is selected (1     b), when I sort the table it looks like this:

3     d
2     c
1     b
0     a

And again row index 1 is selected (2     c), whereas row number 3 is supposed to be selected ((1     b) as before).

Now, what do I miss here, and how I fix it?
0
 
LVL 2

Author Comment

by:s_lavie
Comment Utility
In row number 3 I meant row index 2
0
 
LVL 92

Expert Comment

by:objects
Comment Utility
How's your sort implemented?
0
 
LVL 2

Author Comment

by:s_lavie
Comment Utility
In MyTableModel (that extends DefaultTableModel) I have a sort method:

public void sortTable(JTable table, Comparator comparator)
{
     for (int i = 0; i < getColumnCount(); i++)
     {
          TableColumn column = colModel.getColumn(i);
          column.setHeaderValue(getColumnName(column.getModelIndex()));     // getColumnName() is overriding the getColumnName() in DefaultTableModel.
     }
     table.getTableHeader().repaint();

     Collections.sort(dataVector, comparator);
}
0
 
LVL 92

Expert Comment

by:objects
Comment Utility
You're not firing any event informing listenerer that you have changed the model.
0
 
LVL 16

Expert Comment

by:heyhey_
Comment Utility
and another thing - the overall algorithm should be:

- save the selected row id
- sort
- find the new index for the row with saved id
- select this index.
0
How your wiki can always stay up-to-date

Quip doubles as a “living” wiki and a project management tool that evolves with your organization. As you finish projects in Quip, the work remains, easily accessible to all team members, new and old.
- Increase transparency
- Onboard new hires faster
- Access from mobile/offline

 
LVL 92

Expert Comment

by:objects
Comment Utility
I actually think the selection model listens to the table model, and updates itself. (But I could be wrong).
0
 
LVL 16

Expert Comment

by:heyhey_
Comment Utility
> I actually think the selection model listens to the table model

I agree, but when you sort the table the only possible event to throw is

TableModelEvent(source, 0, max, ALL_COLUMNS, UPDATE);

and SelectionModel will use the same selection index.
0
 
LVL 2

Author Comment

by:s_lavie
Comment Utility
I added the line:
table.tableChanged(new TableModelEvent(this, 0, table.getRowCount() - 1, TableModelEvent.ALL_COLUMNS, TableModelEvent.UPDATE));
After the line:
Collections.sort(dataVector, comparator);

> - save the selected row id
> - sort
> - find the new index for the row with saved id
> - select this index.

That's exactly what I was afraid of:
Find the new index for the row with saved id is quiet heavy isn't it? it means for every selected row I have to run over the entire table!
0
 
LVL 16

Expert Comment

by:heyhey_
Comment Utility
> That's exactly what I was afraid of:

you have to find out the new index for the selected row somehow - there isn't magic solution :)
0
 
LVL 2

Author Comment

by:s_lavie
Comment Utility
Do you have any intelligent solution for saving and finding those indices?
0
 
LVL 16

Expert Comment

by:heyhey_
Comment Utility
ok, let's define the REAL problem:

- you have collection of Objects;
- you rearrange (sort) the items in the collection;
- you want to find the new index for some item, given the old index.

I cannot think of any good solution right now, but maybe somebody else will be able to help you
0
 
LVL 16

Expert Comment

by:heyhey_
Comment Utility
hey, thanks for the points !
0
 
LVL 2

Author Comment

by:s_lavie
Comment Utility
You earned them!
0

Featured Post

Top 6 Sources for Identifying Threat Actor TTPs

Understanding your enemy is essential. These six sources will help you identify the most popular threat actor tactics, techniques, and procedures (TTPs).

Join & Write a Comment

Introduction This article is the first of three articles that explain why and how the Experts Exchange QA Team does test automation for our web site. This article explains our test automation goals. Then rationale is given for the tools we use to a…
Introduction This article is the last of three articles that explain why and how the Experts Exchange QA Team does test automation for our web site. This article covers our test design approach and then goes through a simple test case example, how …
Viewers will learn about the regular for loop in Java and how to use it. Definition: Break the for loop down into 3 parts: Syntax when using for loops: Example using a for loop:
Viewers will learn how to properly install Eclipse with the necessary JDK, and will take a look at an introductory Java program. Download Eclipse installation zip file: Extract files from zip file: Download and install JDK 8: Open Eclipse and …

771 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

13 Experts available now in Live!

Get 1:1 Help Now