Develop Reference

Change the font color in a specific cell of a JTable?

Before starting, I've viewed a handful of solutions as well as documentation. I can't seem to figure out why my code isn't working the way I believe it should work. I've extended DefaultTableCellRenderer but I don't believe it is being applied - that or I messed things up somewhere.
Here are the threads / websites I've looked into before posting this question:
Swing - Is it possible to set the font color of 'specific' text within a JTable cell?
JTable Cell Renderer
http://docs.oracle.com/javase/tutorial/uiswing/components/table.html
I realize the first link uses HTML to change the font color, but I would think the way I went about it should produce the same result.
To make it easier on those who want to help me figure out the issues, I've created an SSCCE.
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Font;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.DefaultTableModel;
public class TableTest {
private static final int IMPORTANT_COLUMN = 2;
public static void createAndShowGUI() {
Object[][] data = new Object[2][4];
//create sample data
String[] realRowData = { "1", "One", "1.0.2", "compile" };
String[] fakeRowData = { "2", "Two", "1.3.2-FAKE", "compile" };
//populate sample data
for(int i = 0; i < realRowData.length; i++) {
data[0][i] = realRowData[i];
data[1][i] = fakeRowData[i];
}
//set up tableModel
JTable table = new JTable();
table.setModel(new DefaultTableModel(data,
new String[] { "ID #", "Group #", "version", "Action" })
{
Class[] types = new Class[] {
Integer.class, String.class, String.class, String.class
};
boolean[] editable = new boolean[] {
false, false, true, false
};
#Override
public Class getColumnClass(int columnIndex) {
return types[columnIndex];
}
#Override
public boolean isCellEditable(int rowIndex, int columnIndex) {
return editable[columnIndex];
}
});
//set custom renderer on table
table.setDefaultRenderer(String.class, new CustomTableRenderer());
//create frame to place table
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setMinimumSize(new Dimension(400, 400));
JScrollPane scrollPane = new JScrollPane();
scrollPane.setViewportView(table);
f.add(scrollPane);
f.pack();
f.setVisible(true);
}
//MAIN
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
//Custom DefaultTableCellRenderer
public static class CustomTableRenderer extends DefaultTableCellRenderer {
public Component getTableCellRenderer(JTable table, Object value,
boolean isSelected, boolean hasFocus, int row, int column)
{
Component c = super.getTableCellRendererComponent(table, value, isSelected,
hasFocus, row, column);
String versionVal = table.getValueAt(row, IMPORTANT_COLUMN).toString();
if(versionVal.contains("FAKE")) {
//set to red bold font
c.setForeground(Color.RED);
c.setFont(new Font("Dialog", Font.BOLD, 12));
} else {
//stay at default
c.setForeground(Color.BLACK);
c.setFont(new Font("Dialog", Font.PLAIN, 12));
}
return c;
}
}
}
My goal is to highlight any value in the version column that contains the word FAKE in a red bold text.

I've extended DefaultTableCellRenderer but I don't believe it is being applied
Some simple debugging tips:
Add a simple System.out.println(...) to the method you think should be invoked
When overriding a method, make sure you use the #Override annotation (you used it in the TableModel class, but not your renderer class).
Your problem is a typing mistake because you are not overriding the proper method:
#Override
// public Component getTableCellRenderer(...) // this is wrong
public Component getTableCellRendererComponent(...)
The override annotation will display a compile message. Try it before changing the code.
Also, your first column is NOT an Integer class. Just because it contains String representations of an Integer does not make it an Integer. You need to add an Integer object to the model.

Replace your custom table cell rendere with the below.
Explanations are in comments. Basically, you should override getTableCellRendererComponent then check for correct column (there may be other methods instead of checking header value), then set cell depending on color.
Do not forget last else block to set color to default if it is not the column you want.
//Custom DefaultTableCellRenderer
public static class CustomTableRenderer extends DefaultTableCellRenderer {
// You should override getTableCellRendererComponent
#Override
public Component getTableCellRendererComponent(JTable table, Object value,
boolean isSelected, boolean hasFocus, int row, int column) {
Component c = super.getTableCellRendererComponent(table, value, isSelected,
hasFocus, row, column);
// Check the column name, if it is "version"
if (table.getColumnName(column).compareToIgnoreCase("version") == 0) {
// You know version column includes string
String versionVal = (String) value;
if (versionVal.contains("FAKE")) {
//set to red bold font
c.setForeground(Color.RED);
c.setFont(new Font("Dialog", Font.BOLD, 12));
} else {
//stay at default
c.setForeground(Color.BLACK);
c.setFont(new Font("Dialog", Font.PLAIN, 12));
}
} else {
// Here you should also stay at default
//stay at default
c.setForeground(Color.BLACK);
c.setFont(new Font("Dialog", Font.PLAIN, 12));
}
return c;
}
}

Component.getWidth() returns 0 in different context

I have a custom TableCellRenderer for which I want to display a different tooltip depending on where in the cell the mouse is positioned. The issue I'm running into is that getWidth() is always returning 0 when called from getToolTipText.
Here's an SSCCE:
import javax.swing.*;
import javax.swing.table.TableCellRenderer;
import java.awt.*;
import java.awt.event.MouseEvent;
public class Sandbox {
public static void main(String[] args) {
JFrame testFrame = new JFrame("Test");
testFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
testFrame.setLayout(new BorderLayout());
JTable testTable = new JTable(new Object[][]{{"Value 1", null}}, new Object[] {"Column 1", "Column 2"});
testTable.getColumnModel().getColumn(1).setCellRenderer(new CustomCellRenderer());
testFrame.add(new JScrollPane(testTable), BorderLayout.CENTER);
testFrame.pack();
testFrame.setLocationRelativeTo(null);
testFrame.setVisible(true);
}
private static class CustomCellRenderer implements TableCellRenderer {
private final JLabel renderer = new JLabel()
{
#Override
protected void paintComponent(Graphics g) {
g.setColor(Color.RED);
g.fillRect(0, 0, getWidth(), getHeight());
System.out.println("Width from paintComponent = " + getWidth());
}
#Override
public String getToolTipText(MouseEvent event) {
System.out.println("Width from getToolTipText = " + getWidth());
return super.getToolTipText(event);
}
};
#Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected,
boolean hasFocus, int row, int column)
{
return renderer;
}
}
}
You can see that the component has been sized and the correct result is printed from the paintComponent method. However, when you hover your mouse over the cell in "Column 2", the getToolTipText method doesn't print the same value.
I found similar questions asked before, but the answer is generally that the Component hasn't been sized yet. In my case, the component has clearly been sized. Can someone please explain why getWidth() returns 0 in the getToolTipText method? Is there a better way to do this?

Override the getToolTipText() method of the JTable:
JTable testTable = new JTable(new Object[][]{{"Value 1", null}}, new Object[] {"Column 1", "Column 2"})
{
#Override
public String getToolTipText(MouseEvent event)
{
JTable table = (JTable)event.getSource();
int column = table.columnAtPoint( event.getPoint() );
if (column == 1)
{
int row = table.rowAtPoint( event.getPoint() );
Rectangle r = table.getCellRect(row, column, false);
Point p = new Point(event.getX() - r.x, event.getY() - r.y);
// System.out.println("Width from getToolTipText = " + r.width);
return p.toString();
}
return super.getToolTipText(event);
}
};
If you want to set the tool tip in the renderer, the code should be in the getTableCellRenderComponent() method. In this case you would then need to use the MouseInfo class to get the current mouse location and convert the location to be relative to the table cell. Something like:
#Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected,
boolean hasFocus, int row, int column)
{
Point pointInTable = MouseInfo.getPointerInfo().getLocation();
SwingUtilities.convertPointFromScreen(pointInTable, table);
Rectangle r = table.getCellRect(row, column, false);
Point p = new Point(pointInTable.x - r.x, pointInTable.y - r.y);
table.setToolTipText(p.toString());
return renderer;
}

You are seeing the result of getWidth() from the same JLabel in two different contexts:
In paintComponent(), the JLabel that has been added to a CellRendererPane which invokes validate() to calculate the width.
In getToolTipText(), the label accessed by the table's ToolTipManager has not been validated.
There's an example of using CellRendererPane here.

Customizing my Cell Renderer to change one cells colour?

note: this code is not mine, I have taken it from another site and i'm simply trying to modify it.
I have a JTable with a load of details however, I want it so that when I change a particular cell for the first cell to change colour. Currently this code just highlights the row when I click on it, but I want it so that if I change one of the values to another number, the name cell for example to change red. I have tried a few things (if statements) but can't seem to work it. Any help would be great.
import javax.swing.*;
import javax.swing.table.*;
import java.awt.*;
public class CustomCellRenderer{
JTable table;
TableColumn tcol;
public static void main(String[] args) {
new CustomCellRenderer();
}
public CustomCellRenderer(){
JFrame frame = new JFrame("Creating a Custom Cell Reanderer!");
JPanel panel = new JPanel();
String data[][] = {{"Vinod","Computer","3"},
{"Rahul","History","2"},
{"Manoj","Biology","4"},
{"Sanjay","PSD","5"}};
String col [] = {"Name","Course","Year"};
DefaultTableModel model = new DefaultTableModel(data,col);
table = new JTable(model);
tcol = table.getColumnModel().getColumn(0);
tcol.setCellRenderer(new CustomTableCellRenderer());
tcol = table.getColumnModel().getColumn(1);
tcol.setCellRenderer(new CustomTableCellRenderer());
tcol = table.getColumnModel().getColumn(2);
tcol.setCellRenderer(new CustomTableCellRenderer());
JTableHeader header = table.getTableHeader();
header.setBackground(Color.yellow);
JScrollPane pane = new JScrollPane(table);
panel.add(pane);
frame.add(panel);
frame.setSize(500,150);
frame.setUndecorated(true);
frame.getRootPane().setWindowDecorationStyle(JRootPane.PLAIN_DIALOG);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
public class CustomTableCellRenderer extends DefaultTableCellRenderer{
public Component getTableCellRendererComponent (JTable table,
Object obj, boolean isSelected, boolean hasFocus, int row, int column) {
Component cell = super.getTableCellRendererComponent(
table, obj, isSelected, hasFocus, row, column);
if (isSelected) {
cell.setBackground(Color.green);
}
else {
if (row % 2 == 0) {
cell.setBackground(Color.lightGray);
}
else {
cell.setBackground(Color.lightGray);
}
}
return cell;
}
}
}

If you know row number you want to highlight just add in the end of the getTableCellRendererComponent method
if (row==theRowNumberToHighlight && column=0) {
cell.setForeground(Color.red);
}

Assuming your table model extends AbstractTableModel, extend TableModelListener. Use the following tableChanged method to figure out when to call your renderer:
public void tableChanged(TableModelEvent e)
{
if (e.getColumn() == columnYouAreChecking && e.getFirstRow() == rowYouAreChecking && e.getLastRow() == rowYouAreChecking)
{
// Change cell color here.
}
}
This code will get called every time the data in your table changes.

Table Cell Editor issue

I'm building a custom table cell editor so it adjusts row height during editing. I have this code, but instead of resizing the cell it seams to resize the whole panel, or the frame. When I try to enter a character in a cell the main frame width narrows down to a couple of pixels.
Can anyone see the problem?
class MyTableCellEditor extends AbstractCellEditor implements TableCellEditor {
MyTextpane component = new MyTextpane();
MyTable table;
private int row;
private int col;
public Component getTableCellEditorComponent(JTable table, Object value, boolean isSelected,
int rowIndex, int vColIndex) {
((MyTextpane) component).setText((String) value);
component.addKeyListener(new KeyListener1());
this.table =(MyTable) table;
this.row = rowIndex;
this.col = vColIndex;
return component;
}
public Object getCellEditorValue() {
return ((MyTextpane) component).getText();
}
public class KeyListener1 implements KeyListener {
#Override
public void keyTyped(KeyEvent ke) {
}
#Override
public void keyPressed(KeyEvent ke) {
}
#Override
public void keyReleased(KeyEvent ke) {
adjustRowHeight(table, row, col);
}
private java.util.List<java.util.List<Integer>> rowColHeight = new ArrayList<java.util.List<Integer>>();
private void adjustRowHeight(JTable table, int row, int column) {
//The trick to get this to work properly is to set the width of the column to the
//textarea. The reason for this is that getPreferredSize(), without a width tries
//to place all the text in one line. By setting the size with the with of the column,
//getPreferredSize() returnes the proper height which the row should have in
//order to make room for the text.
int cWidth = table.getTableHeader().getColumnModel().getColumn(column).getWidth();
setSize(new Dimension(cWidth, 1000));
int prefH = getPreferredSize().height;
while (rowColHeight.size() <= row) {
rowColHeight.add(new ArrayList<Integer>(column));
}
java.util.List<Integer> colHeights = rowColHeight.get(row);
while (colHeights.size() <= column) {
colHeights.add(0);
}
colHeights.set(column, prefH);
int maxH = prefH;
for (Integer colHeight : colHeights) {
if (colHeight > maxH) {
maxH = colHeight;
}
}
if (table.getRowHeight(row) != maxH) {
table.setRowHeight(row, maxH);
}
}
}
}

have look at
my answer about doLayout(could be fired from CellEditor)
or (more than confortable way to use TextUtils) comment by #kleopatra about getPreferredSize
this could (very) confusing the users,
because I miss JScrollPane, there have to override MaxSize, max size is height & weight for JScrollPane, otherwise part of CellEditor can going outside of screeens bounds .........,
don't do that, put there JScrollPane with JTextComponents, override PreferredSize for CellEditor,
everything are wrong, my view,
create applications modal popup window (based only on JDialog, becasue JWindow doesn't alloved input to the JTextComponent) with JTextComponent, implements there KeyBindings for ESC key, the same for lost Fucus for JDialog, then could be undecorated without any issue
put there Save JButton
output from Save Button reditect to the selected cell, you can't lost focus from application modal inside JTable
contents should be formatted, filtered, modified one JDialog for all cells from JTable

As an alternative to resizing the row while editing, consider TablePopupEditor, which uses JTextArea.

JTable with cell flashing

I am writing an application using the Swing library in Java. I have a table component that extends JTable, and in this component I have overridden the method getTableCellRendererComponent, because I color the cells of the table. I have a custom table model (that extends from the default table model), and the table component itself I have added to a JPanel. All this works.
Now I would like to add to this table, some functionality to have a cell flashing. Potentially, more than one cell can be flashing at a time, i.e. cells at (row 1, column 2) and (row 3, column 4).
Is this possible to do? Any hints that could get me started would be appreciated.

I find one article for your answer:
http://www.devx.com/DevX/10MinuteSolution/17167/0/page/1
The page provide the source code for downloading.
Basically it use following method to notify table to update the cell timely.
JTable.tableChanged(new TableModelEvent(table.getModel(), firstRow, lastRow, column));
After reading his code, I sort out a simpler version of his code, you can change my code or use his code (more elegant but also more complex).
public class FlashCellTable
{
public static Color color;
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setSize(800, 600);
final JTable table = new JTable(4, 4);
table.setDefaultRenderer(Object.class, new MyFlashingCellRenderer());
table.setValueAt("Flashing", 0, 0);
frame.getContentPane().add(new JScrollPane(table));
final long startTime = System.currentTimeMillis();
Thread thread = new Thread()
{
#Override
public void run()
{
while (true)
{
long now = System.currentTimeMillis();
long second = (now - startTime) / 1000;
color = second / 2 * 2 == second ? Color.red : Color.blue;
System.out.println("FlashCellTable.run");
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
table.tableChanged(new TableModelEvent(table.getModel(), 0, 0, 0));
}
});
try
{
Thread.sleep(1000);
}
catch(InterruptedException e)
{
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
}
}
}
};
thread.start();
frame.setVisible(true);
}
public static class MyFlashingCellRenderer extends DefaultTableCellRenderer
{
#Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus,
int row, int column)
{
JLabel label =
(JLabel)super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
if ("Flashing".equals(value))
{
label.setBackground(color);
}
else
{
label.setBackground(Color.white);
}
return label;
}
}
}