Java swing setSelectionForeground performance issue

Question

I think I have a weird problem here. Here is my code:

private class BorderCellRenderer extends DefaultTableCellRenderer {
    private Border extraBorder;
    /**
     * A cell render is based on labels which are changed to display the correct appearance
     * This cell renderer adds extra border to every render action
     */
    BorderCellRenderer(Border extraBorder) {
        this.extraBorder = extraBorder;
    }


    /**
     * The setBorder() is used to change the cell appearance.
     * The trick is to override the call (of JComponent) and to add extra space
     * to it by making it an compound border with.
     *
     * Remember that getBorder() now returns our compound border
     */
    public void setBorder(Border border) {
        super.setBorder(new CompoundBorder(border, extraBorder));
    }

    public Component getTableCellRendererComponent(JTable table, Object value,
                                                    boolean isSelected, boolean hasFocus,
                                                    int row, int column) {
        setFont(table.getFont());
        setText(value.toString());

        /* set color depending on the state of the row */
        TableRowItem rowItem = ((FooModel) table.getModel()).getRow(row);

        String state = rowItem.getState();

        /* set tool tip on EMPLOYEE column */
        if(column == FooModel.COL_EMPLOYEE) {
            setToolTipText("blalba");
        }

        /* Paint text according to state*/
        if(state.equals(RowItemState.ENTERED)) {
            setForeground(Color.black);
            //TODO setSelectionForeground(Color.black);
        }
        if(state.equals(RowItemState.SUBMITTED)) {
            setForeground(Color.blue);
            //TODO setSelectionForeground(Color.blue);
        }
        if(state.equals(RowItemState.APPROVED)) {
            Color green = new Color(0, 128, 0); // greenish
            setForeground(green);
            //TODO setSelectionForeground(green);
        }
        if(state.equals(RowItemState.BOOKED)) {
            setForeground(Color.red);
            //TODO setSelectionForeground(Color.red);
        }

            switch (column) {
            case FooModel.COL_EMPLOYEE:
            case FooModel.COL_SAT:
            case FooModel.COL_SUN:
                if(state.equals(RowItemState.CHECKED)) {
                    setBackground(new Color(183, 244,176)); //light green
                } else {
                    setBackground(java.awt.Color.lightGray);
                }
                break;
            default:
                if(state.equals(RowItemState.CHECKED)) {
                    setBackground(new Color(183, 244,176)); //light green
                } else {
                    setBackground(java.awt.Color.white);
                }
                break;
            }
       //}

        if (column == FooModel.COL_TOTAL){
            if (table.getSelectedRowCount() > 0){
                int rowsSelected[] = table.getSelectedRows();
                double total = 0;
                for (int j = 0; j < table.getSelectedRowCount(); j++){
                    Double dTemp = (Double) table.getValueAt(rowsSelected[j], FooModel.COL_TOTAL);
                    total += dTemp.doubleValue();
                }
                setToolTipText("Total Selected = " + String.valueOf(total));
            }
        }

        // return super method for selections
        return super.getTableCellRendererComponent(table, value,
                                                    isSelected, hasFocus,
                                                    row, column);
    }
}

Now we get to the fun part. This code example runs fine, however when I uncomment the TODO lines so that the setSelectionForeground() methods are called, my CPU gets to like 20% on a Quad-Core. This happens on all my colleagues PC's as well (also Quad-Cores). When the lines are commented, CPU is around 0-1%. I find this very strange and cannot figure out what is going wrong here. I hope you can help me.

Seeing as `DefaultTableCellRenderer` doesn't have `setSelectionForeground`, I would assume this is a inner class of something like, a `JTable` you've implemented, which would then suggest that each time you call `setSelectionForeground`, the table is trying to re-render any cells that might be selected, as well as fire property change events and generally getting itself caught in a nasty loop of updates... — MadProgrammer, Jul 29 '13 at 08:06
This is indeed an inner class of a JTable. So do you mean that setSelectionForeground is a method of the JTable and not the renderer? — lugte098, Jul 29 '13 at 08:11
That's correct. Try typing `this.setSelectionForeground(Color.BLUE)` within the context of the cell renderer and see if it will compile. — MadProgrammer, Jul 29 '13 at 08:15
you're right, ok so now i need to find out how to get it working using other methods — lugte098, Jul 29 '13 at 08:20
the job of the renderer is to ... render :-) **Nothing else**. F.i. calculation of the actual tooltip belongs elsewhere (f.i. into a selectionListener) And - as already noted, just for emphasis - **don't** change the state of the caller (here: the table), ever — kleopatra, Jul 29 '13 at 08:22

score 6 · Accepted Answer · answered Jul 29 '13 at 08:07

6

Invoking setSelectionForeground() schedules a call to repaint() each of the four times time it is called for every cell. Instead,

Do not call setSelectionForeground() in the renderer.
Condition the color once based on the value of isSelected.

answered Jul 29 '13 at 08:07

trashgod

203,806
29
246
1,045

So how do i go about setting it once? I am kind of new to swing. – lugte098 Jul 29 '13 at 08:13
@lugte098 They way you have it right now should work just fine (ie `setForgroud` etc) – MadProgrammer Jul 29 '13 at 08:16
yes it works fine, but when i select a row it turns black again. So for selected items i need something else – lugte098 Jul 29 '13 at 08:19
There is no method to change the color of a selected row separately? – lugte098 Jul 29 '13 at 09:12
@lugte098: overriding `prepareRenderer()` works well for changes based on location, as shown in mKorbel's [example](http://stackoverflow.com/q/7132400/714968). – trashgod Jul 29 '13 at 09:15
Thanks, this was indeed the fix for my solution. I overridden the prepareRenderer and used the isSelected there to get what i wanted. – lugte098 Jul 29 '13 at 10:14

score 2 · Answer 2 · answered Jul 29 '13 at 08:11

2

use

and to test coordinates boolean isSelected, boolean hasFocus, int row, int column (isSelected/hasFocus)
getValue from XxxTableModel by strictly convertViewToModel (e.g. JTables view can be sorted or filtered)
job for prepareRenderer

answered Jul 29 '13 at 08:11

mKorbel

109,525
20
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319

I dont really get what you are saying atm – lugte098 Jul 29 '13 at 08:13
2

+1 for `convertXxx()`, which is easily overlooked until someone moves a column. – trashgod Jul 29 '13 at 08:34
1

@lugte098 [see and uncomment code](http://stackoverflow.com/q/7132400/714968) the same for rest of XxxRenderers – mKorbel Jul 29 '13 at 08:47

Java swing setSelectionForeground performance issue

2 Answers2