The cell renderers in tables and lists are used like a "stamp". One component is used for painting all the cells. Also see Concepts: Editors and Renderers. If you want to retain the information about the "highlighted" cells, you somehow have to store them.
An example (extended based on the comments) :
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.TableColumn;
import javax.swing.table.TableColumnModel;
public class CellRendererTest
{
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
@Override
public void run()
{
createAndShowGUI();
}
});
}
private static void createAndShowGUI()
{
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
String[] columnNames = {
"First Name", "Last Name", "Sport" };
Object[][] data = {
{"Kathy", "Smith", "Snowboarding" },
{"John", "Doe", "Rowing" },
{"Sue", "Black", "Knitting"},
{"Jane", "White", "Speed reading"},
{"Joe", "Brown", "Pool"}
};
final JTable table = new JTable(data, columnNames);
final ColoringCellRenderer cellRenderer = new ColoringCellRenderer();
TableColumnModel columnModel = table.getColumnModel();
int cc = columnModel.getColumnCount();
for (int c=0; c<cc; c++)
{
TableColumn column = columnModel.getColumn(c);
column.setCellRenderer(cellRenderer);
}
JScrollPane scrollPane = new JScrollPane(table);
f.getContentPane().setLayout(new BorderLayout());
f.getContentPane().add(scrollPane, BorderLayout.CENTER);
JButton addRandomColorButton = new JButton("Add random color");
addRandomColorButton.addActionListener(new ActionListener()
{
private Random random = new Random(0);
@Override
public void actionPerformed(ActionEvent e)
{
int rows = table.getRowCount();
int cols = table.getColumnCount();
int row = random.nextInt(rows);
int col = random.nextInt(cols);
int r = random.nextInt(255);
int g = random.nextInt(255);
int b = random.nextInt(255);
cellRenderer.setCellColor(row, col, new Color(r,g,b));
table.repaint();
}
});
f.getContentPane().add(addRandomColorButton, BorderLayout.SOUTH);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
}
class ColoringCellRenderer extends DefaultTableCellRenderer
{
private final Map<Point, Color> cellColors = new HashMap<Point, Color>();
void setCellColor(int r, int c, Color color)
{
if (color == null)
{
cellColors.remove(new Point(r,c));
}
else
{
cellColors.put(new Point(r,c), color);
}
}
private Color getCellColor(int r, int c)
{
Color color = cellColors.get(new Point(r,c));
if (color == null)
{
return Color.WHITE;
}
return color;
}
@Override
public Component getTableCellRendererComponent(JTable table, Object value,
boolean isSelected, boolean hasFocus, int row, int column)
{
super.getTableCellRendererComponent(
table, value, isSelected, hasFocus, row, column);
Color color = getCellColor(row, column);
setBackground(color);
return this;
}
}
EDIT: The remaining part was from the original answer, using only a single cell color. The new one above is more complete (and more powerful, because it can emulate the single-color renderer), but I'll leave this here for completeness
This could be achieved with a renderer like this one:
class ColoringCellRenderer extends DefaultTableCellRenderer
{
private final Set<Point> highlightedCells = new HashSet<Point>();
void setHighlighted(int r, int c, boolean highlighted)
{
if (highlighted)
{
highlightedCells.add(new Point(r,c));
}
else
{
highlightedCells.remove(new Point(r,c));
}
}
private boolean isHighlighted(int r, int c)
{
return highlightedCells.contains(new Point(r,c));
}
public Component getTableCellRendererComponent(JTable table, Object value,
boolean isSelected, boolean hasFocus, int row, int column)
{
if (isHighlighted(row, column))
{
setForeground(Color.BLACK);
setBackground(Color.RED);
}
else
{
setForeground(Color.BLACK);
setBackground(Color.WHITE);
}
return this;
}
}
You can then create an instance of this renderer, and add or remove cells to be highlighted:
ColoringCellRenderer r = new ColoringCellRenderer();
// Assign renderer to table...
...
// Later, highlight cells:
r.setHighlighted(4,2,true);
r.setHighlighted(6,1,true);
r.setHighlighted(1,5,false);
...
If you want different colors for the cells, you could replace the Set with a Map that maps a particular Point (representing the row/column of the cell) to a Color object.
