JTable: setSelectionBackground with columnMargin

Question

I have a JTable in which I'm setting a selection background color.
objectTable.setSelectionBackground( new Color( 0xCC, 0xCC, 0xFF ) );
I'm also setting a column margin using :
DefaultTableColumnModel colModel = (DefaultTableColumnModel) objectTable.getColumnModel( );
colModel.setColumnMargin( 12 );
When you select a row in the table, the selection background is only used for
the cells themselves, excluding the margins. You end up with selected cells
interspersed with white margins.
Anyone know of a reasonably simple way to get the margins around a selected
cell to paint with the selection background color?

Answer 1

I have a JTable in which I'm setting a selection
background color.
objectTable.setSelectionBackground( new Color( 0xCC,
0xCC, 0xFF ) );
I'm also setting a column margin using :
DefaultTableColumnModel colModel =
(DefaultTableColumnModel)
objectTable.getColumnModel( );
olModel.setColumnMargin( 12 );
When you select a row in the table, the selection
background is only used for
the cells themselves, excluding the margins. You end
up with selected cells
interspersed with white margins.
Anyone know of a reasonably simple way to get the
margins around a selected
cell to paint with the selection background color?The margin, by definition, is the space between cells, so it plays no part in selection and such. I think Michael is on the right track. Forget about the margin, do the work in the renderer. See example below.
Jim S.
=================
import java.awt.Color;
import java.awt.Component;
import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.border.Border;
import javax.swing.table.DefaultTableCellRenderer;
public class MarginTest {
    MarginTest() {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        String[][] data = new String[10][10];
        String[] columnNames = new String[10];
        for (int i = 0; i < 10; i++) {
            for (int j = 0; j < 10; j++) {
                data[i][j] = "<" + i + "," + j + ">";
            columnNames[i] = "Column " + i;
        JTable t = new JTable(data, columnNames);
        t.setDefaultRenderer(Object.class, new MyRenderer());
        f.add(new JScrollPane(t));
        f.setSize(400, 300);
        f.setVisible(true);
    public static void main(String[] args) {
        new MarginTest();
    static class MyRenderer extends DefaultTableCellRenderer {
        private Border CACHED_SEL_BORDER = BorderFactory.createMatteBorder(
                0,
                6,
                0,
                6,
                UIManager.getColor("Table.selectionBackground"));
        private Border CACHED_BORDER = BorderFactory.createMatteBorder(
                0,
                6,
                0,
                6,
                UIManager.getColor("Table.background"));
        public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected,
                boolean hasFocus, int row, int column) {
            super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
            Border currentBorder = getBorder();
            if(isSelected) {
                ((JComponent)this).setBorder(BorderFactory.createCompoundBorder(currentBorder, CACHED_SEL_BORDER));
            } else {
                ((JComponent)this).setBorder(BorderFactory.createCompoundBorder(currentBorder, CACHED_BORDER));
            return this;
}