AJAX definitely has the buzz right now, but it might not be the right thing for you. AJAX is limited to the latest browsers, exposes browser compatibility issues, and requires new skill-sets for many. There is a good blog entry by Alex Bosworth on AJAX Mistakes which is a good read before you jump full force into AJAX.
On the other hand you can achieve highly interactive rich web applications that are responsive and appear really fast.
While it is debatable as to whether an AJAX based application is really faster, the user feels a sense of immediacy because they are given active feedback while data is exchanged in the background. If you are an early adopter and can handle the browser compatibility issues, and are willing to learn some more skills, then AJAX is for you. It may be prudent to start off AJAX-ifying a small portion or component of your application first. We all love technology, but just remember the purpose of AJAX is to enhance your user's experience and not hinder it.
Does AJAX work with Java?
Absolutely. Java is a great fit for AJAX! You can use Java Enterprise Edition servers to generate AJAX client pages and to serve incoming AJAX requests, manage server side state for AJAX clients, and connect AJAX clients to your enterprise resources. The JavaServer Faces component model is a great fit for defining and using AJAX components.
Won't my server-side framework provide me with AJAX?
You may be benefiting from AJAX already. Many existing Java based frameworks already have some level of AJAX interactions and new frameworks and component libraries are being developed to provide better AJAX support. I won't list all the Java frameworks that use AJAX here, out of fear of missing someone, but you can find a good list at www.ajaxpatterns.org/Java_Ajax_Frameworks.

If you have not chosen a framework yet it is recommended you consider using JavaServer Faces or a JavaServer Faces based framework. JavaServer Faces components can be created and used to abstract many of the details of generating JavaScript, AJAX interactions, and DHTML processing and thus enable simple AJAX used by JSF application developer and as plug-ins in JSF compatible IDE's, such as Sun Java Studio Creator.

Where should I start?
Assuming the framework you are using does not suffice your use cases and you would like to develop your own AJAX components or functionality I suggest you start with the article Asynchronous JavaScript Technology and XML (AJAX) With Java 2 Platform, Enterprise Edition.
If you would like to see a very basic example that includes source code you can check out the tech tip Using AJAX with Java Technology. For a more complete list of AJAX resources the Blueprints AJAX Home page.
Next, I would recommend spending some time investigating AJAX libraries and frameworks. If you choose to write your own AJAX clients-side script you are much better off not re-inventing the wheel.

What do I need to know to create my own AJAX functionality?
If you plan not to reuse and existing AJAX component here are some of the things you will need to know.
Plan to learn

Dynamic HTML (DHTML), the technology that is the foundation for AJAX. DHTML enables browser-base realtime interaction between a user and a web page. DHTML is the combination of JavaScript, the Document Object Model (DOM) and Cascading Style Sheets (CSS).

function AJAXInteraction(url, callback) {

var req = init();
req.onreadystatechange = processRequest;

function init() {
if (window.XMLHttpRequest) {
return new XMLHttpRequest();
} else if (window.ActiveXObject) {
return new ActiveXObject("Microsoft.XMLHTTP");
}
}

function processRequest () {
if (req.readyState == 4) {
if (req.status == 200) {
if (callback) callback(req.responseXML);
}
}
}

this.doGet = function() {
req.open("GET", url, true);
req.send(null);
}

this.doPost = function(body) {
req.open("POST", url, true);
req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
req.send(body);
}
}

function makeRequest() {
var ai = new AJAXInteraction("processme", function() {
alert("Doing Post Process");});
ai.doGet();
}
	

		
<form onSubmit="doAJAXSubmit();return false;" >
<input type="text" id="tf1" />
<input type="submit" id="submit1" value="Update"/>
</>

	 
<form onSubmit="doAJAXSubmit();return false;" >
<input type="text" id="tf1" />
<input type="button" id="button1" onClick="doAJAXSubmit()" value="Update"/>
</>

function updateOnServer(oldId, oldValue, itemId, itemValue) {
var bindArgs = {
url:  "faces/ajax-dlabel-update",
method: "post",
content: {"component-id": itemId, "component-value": itemValue},
mimetype: "text/xml",
load: function(type, data) {
processUpdateResponse(data);
},
backButton: function() {
alert("old itemid was " + oldId);
},
forwardButton: function(){
alert("forward we must go!");
}
};
dojo.io.bind(bindArgs);
}

<categories>
<category>
<cat-id>1</cat-id>
<name>Books</name>
<description>Fun to read</description>
<image-url>books_icon.gif</image-url>
</category>
<category>
<cat-id>2</cat-id>
<name>Electronics</name>
<description>Must have gadgets</description>
<image-url>electronics.gif</image-url>
</category>
</categories>

<scrip type="text/javascript" >

...

function addCategory(id, name, imageSrc) {

var categoryTable = document.getElementById("categoryTable");
var row = document.createElement("tr");
var catCell = document.createElement("td");
var img = document.createElement("img");
img.src = ("images\\" + imageSrc);
var link = document.createElement("a");
link.className ="category";
link.appendChild(document.createTextNode(name));
link.setAttribute("onclick", "catalog?command=category&catid=" + id);
catCell.appendChild(img);
catCell.appendChild(link);
row.appendChild(catCell);
categoryTable.appendChild(row);
}
</script>

...

<table>
<tr>
<td width="300" bgoclor="lightGray">
<table id="categoryTable" border="0" cellpadding="0"></table>
</td>
<td id="body" width="100%">Body Here</td>
</tr>
</table>
		

function checkForMessage() {
// start AJAX interaction with processCallback as the callback function
}

// callback for the request
function processCallback() {

// do post processing

setTimeout("checkForMessage()", 10000);
}

public final void clone() throws java.lang.CloneNotSupportedException {
throw new java.lang.CloneNotSupportedException();
}
If you want your class to be cloneable, and you've considered the
consequences of that choice, then you can still protect yourself. If you're
defining a clone method yourself, make it final. If you're relying on a
nonfinal clone method in one of your superclasses, then define this
method:
public final void clone() throws java.lang.CloneNotSupportedException {
super.clone();
}

Make your classes nonserializeable

Serialization is dangerous because it allows adversaries to get their hands on the internal state of your objects. An adversary can serialize one of your objects into a byte array that can be read. This allows the adversary to inspect the full internal state of your object, including any fields you marked private, and including the internal state of any objects you reference.
To prevent this, you can make your object impossible to serialize. To achieve this goal, declare the writeObject method:

width.addChangeListener(updater);
height.addChangeListener(updater);
// Lay it all out.
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

Container c = f.getContentPane();
c.setLayout(new BorderLayout());
c.add(width, BorderLayout.NORTH);
c.add(height, BorderLayout.WEST);
c.add(dynamicLabel, BorderLayout.CENTER);
f.setSize(210,210);
f.setVisible(true);
}
}

HtmlLabel
/* HtmlLabel.java
A JLabel that uses inline HTML to format its text.
*/
import javax.swing.*;
public class HtmlLabel extends JPanel {
public static final String markup = "line 1" + "big blue line 2 line 3";
public static void main(String argv[]) {
JPanel p = new JPanel(new java.awt.GridLayout(0, 1));
p.add(new JLabel(markup)); p.add(new java.awt.Label(markup));
JFrame f = new JFrame("HtmlLabel");
f.setContentPane(p); f.setSize(600, 200);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
}

ProgressBarExample
/* ProgressBarExample.java
A demonstration of the JProgressBar component. The component tracks the
progress of a for loop.
*/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ProgressBarExample extends JPanel {

JProgressBar pbar;
static final int MY_MINIMUM=0;
static final int MY_MAXIMUM=100;
public ProgressBarExample() {
pbar = new JProgressBar();
pbar.setMinimum(MY_MINIMUM);
pbar.setMaximum(MY_MAXIMUM);
add(pbar);
}

public void updateBar(int newValue) {
pbar.setValue(newValue);
}
public static void main(String args[]) {
final ProgressBarExample it = new ProgressBarExample();
JFrame frame = new JFrame("Progress Bar Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(it);
frame.pack();
frame.setVisible(true);

for (int i = MY_MINIMUM; i <= MY_MAXIMUM; i++) {
final int percent=i;
try {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
it.updateBar(percent);
}
});
java.lang.Thread.sleep(100);
} catch (InterruptedException e) {;}
}
}
}

ProgressMonitorInputExample
/* ProgressMonitorInputExample.java
Simpilar to the ProgressMonitorExample except that we can now use an
actual input file to monitor rather than inducing progress manually.
The file to load should be passed as a command line argument.
*/
import java.io.*;
import java.awt.*;
import javax.swing.*;

public class ProgressMonitorInputExample {
public ProgressMonitorInputExample(String filename) {
ProgressMonitorInputStream monitor;
try {
monitor = new ProgressMonitorInputStream(
null, "Loading "+filename, new FileInputStream(filename));
while (monitor.available() > 0) {
byte[] data = new byte[38];
monitor.read(data);
System.out.write(data);
}
} catch (FileNotFoundException e) {
JOptionPane.showMessageDialog(null, "Unable to find file: "
+ filename, "Error", JOptionPane.ERROR_MESSAGE);
} catch (IOException e) {;}
}

public static void main(String args[]) {
new ProgressMonitorInputExample(args[0]);
}
}

SplashScreen
/* SplashScreen.java
A simple application to show a title screen in the center of the screen
for the amount of time given in the constructor. This class includes
a sample main() method to test the splash screen, but it's meant for use
with other applications.
*/

import java.awt.*;
import javax.swing.*;

public class SplashScreen extends JWindow {
private int duration;
public SplashScreen(int d) {
duration = d;
}

// A simple little method to show a title screen in the center
// of the screen for the amount of time given in the constructor
public void showSplash() {
JPanel content = (JPanel)getContentPane();
content.setBackground(Color.white);
// Set the window's bounds, centering the window
int width = 450;
int height =115;
Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
int x = (screen.width-width)/2;
int y = (screen.height-height)/2;
setBounds(x,y,width,height);

// Build the splash screen
JLabel label = new JLabel(new ImageIcon("oreilly.gif"));
JLabel copyrt = new JLabel
("Copyright 2002, O'Reilly & Associates", JLabel.CENTER);
copyrt.setFont(new Font("Sans-Serif", Font.BOLD, 12));
content.add(label, BorderLayout.CENTER);
content.add(copyrt, BorderLayout.SOUTH);
Color oraRed = new Color(156, 20, 20, 255);
content.setBorder(BorderFactory.createLineBorder(oraRed, 10));

// Display it
setVisible(true);
// Wait a little while, maybe while loading resources
try { Thread.sleep(duration); } catch (Exception e) {}

setVisible(false);
}
public void showSplashAndExit() {
showSplash();
System.exit(0);
}
public static void main(String[] args) {
// Throw a nice little title page up on the screen first
SplashScreen splash = new SplashScreen(10000);
// Normally, we'd call splash.showSplash() and get on with the program.
// But, since this is only a test...
splash.showSplashAndExit();
}
}

ThumbNailFileView
/* ThumbNailFileView.java
A simple implementation of the FileView class that provides a 16x16 image of
each GIF or JPG file for its icon. This could be SLOW for large images, as we
simply load the real image and then scale it.
*/
import java.io.File;
import java.awt.*;
import javax.swing.*;
import javax.swing.filechooser.*;
import javax.swing.plaf.metal.MetalIconFactory;

public class ThumbNailFileView extends FileView {
private Icon fileIcon = MetalIconFactory.getTreeLeafIcon();
private Icon folderIcon = MetalIconFactory.getTreeFolderIcon();
private Component observer;

public ThumbNailFileView(Component c) {
// We need a component around to create our icon’s image
observer = c;
}

public String getDescription(File f) {
// We won’t store individual descriptions, so just return the
// type description.
return getTypeDescription(f);
}

public Icon getIcon(File f) {
// Is it a folder?
if (f.isDirectory()) { return folderIcon; }

// Ok, it’s a file, so return a custom icon if it’s an image file
String name = f.getName().toLowerCase();
if (name.endsWith(".jpg") || name.endsWith(".gif")) {
return new Icon16(f.getAbsolutePath());
}
// Return the generic file icon if it’s not
return fileIcon;
}
public String getName(File f) {
String name = f.getName();
return name.equals("") ? f.getPath() : name;
}
public String getTypeDescription(File f) {
String name = f.getName().toLowerCase();
if (f.isDirectory()) { return "Folder"; }
if (name.endsWith(".jpg")) { return "JPEG Image"; }
if (name.endsWith(".gif")) { return "GIF Image"; }
return "Generic File";
}

public Boolean isTraversable(File f) {
// We’ll mark all directories as traversable
return f.isDirectory() ? Boolean.TRUE : Boolean.FALSE;
}

public class Icon16 extends ImageIcon {
public Icon16(String f) {
super(f);
Image i = observer.createImage(16, 16);
i.getGraphics().drawImage(getImage(), 0, 0, 16, 16, observer);
setImage(i);
}
public int getIconHeight() { return 16; }
public int getIconWidth() { return 16; }

public void paintIcon(Component c, Graphics g, int x, int y) {
g.drawImage(getImage(), x, y, c);
}
}
}

RoundedLineBorder
/* RoundedLineBorder.java
A simple demontstration of the LineBorder class built with rounded
corners.
*/
import java.awt.*;
import javax.swing.*;
import javax.swing.border.*;
public class RoundedLineBorder extends JPanel {
public RoundedLineBorder() {
super(true);
setLayout(new BorderLayout());
JLabel label = new JLabel("Rounded Corners");
label.setHorizontalAlignment(JLabel.CENTER);
LineBorder line = new LineBorder(Color.blue, 2, true);
label.setBorder(line);
add(label, BorderLayout.CENTER);
}

public static void main(String s[]) {
JFrame frame = new JFrame("Rounded Line Border");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500, 200);
frame.setContentPane(new RoundedLineBorder());
frame.setVisible(true);
}
}

Add a background image in JTable
/* File: Table.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;

public class Table
{
public static void main(String[] args)
{
JFrame frame = new JFrame("Table");
frame.addWindowListener( new WindowAdapter() {
public void windowClosing(WindowEvent e)
{
Window win = e.getWindow();
win.setVisible(false);
win.dispose();
System.exit(0);
}
} );


// Create your own sub-class of JTable rather than using anonymous class
JTable table = new JTable( 15, 3 )
{
public Component prepareRenderer(TableCellRenderer renderer, int row, int column)
{
Component c = super.prepareRenderer( renderer, row, column);
// We want renderer component to be transparent so background image is visible
if( c instanceof JComponent )
((JComponent)c).setOpaque(false);
return c;
}
};

// Use our version of JScrollPane
MyScrollPane sp = new MyScrollPane( table );

// Set the background image
ImageIcon image = new ImageIcon( "codeguruwm.gif" );
sp.setBackgroundImage( image );

frame.getContentPane().add( sp );

frame.pack();
frame.show();
}
}

// File: MyScrollPane.java
import java.awt.*;
import javax.swing.*;
import javax.swing.plaf.metal.*;
import com.sun.java.swing.plaf.motif.*;
import com.sun.java.swing.plaf.windows.*;
class MyScrollPane extends JScrollPane
{
public MyScrollPane(Component view, int vsbPolicy, int hsbPolicy)
{
super( view, vsbPolicy, hsbPolicy );
// Set the component to transparent
if( view instanceof JComponent )
((JComponent)view).setOpaque(false);
}

public MyScrollPane(Component view)
{
this(view, VERTICAL_SCROLLBAR_AS_NEEDED, HORIZONTAL_SCROLLBAR_AS_NEEDED);
}

public MyScrollPane(int vsbPolicy, int hsbPolicy)
{
this(null, vsbPolicy, hsbPolicy);
}

public MyScrollPane()
{
this(null, VERTICAL_SCROLLBAR_AS_NEEDED, HORIZONTAL_SCROLLBAR_AS_NEEDED);
}

public void paint(Graphics g)
{
if( image != null )
{
// Draw the background image
Rectangle d = getViewport().getViewRect();
for( int x = 0; x < d.width; x += image.getIconWidth() )
for( int y = 0; y < d.height; y += image.getIconHeight() )
g.drawImage( image.getImage(), x, y, null, null );
// Do not use cached image for scrolling
getViewport().setBackingStoreEnabled(false);
}
super.paint( g );
}

public void setBackgroundImage( ImageIcon image )
{
this.image = image;
}

ImageIcon image = null;
}

Adding a row
Note that if you are using your own subclass of AbstractTableModel(), this doesn't apply to you. Your TableModel should provide such a feature.
Here's the code snippet you can use to insert a blank row at the end of the table.

if( table.getModel() instanceof DefaultTableModel )
{
int cols = table.getModel().getColumnCount();
((DefaultTableModel)table.getModel()).addRow(new Object[cols]);
}

In the code above, we make a check whether the table model is an instance of a DefaultTableModel. This is required because when you create JTable giving it initial data, Swing creates an anonymous subclass of AbstractTableModel.
If you are using your own TableModel, make sure that addRow() is supported.

Dynamically compute and display the column total in a cell
/*File: TotalRowExample.java
package jp.gr.java_conf.tame.swing.examples;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import java.text.*;
import javax.swing.*;
import javax.swing.table.*;
import javax.swing.event.*;

class DecimalRenderer extends DefaultTableCellRenderer {
DecimalFormat formatter;

DecimalRenderer(String pattern) {
this(new DecimalFormat(pattern));
}

DecimalRenderer(DecimalFormat formatter) {
this.formatter = formatter;
setHorizontalAlignment(JLabel.RIGHT);
}

public void setValue(Object value) {
setText((value == null) ? ""
: formatter.format(((Double)value).doubleValue()));
}
}

public class TotalRowExample extends JFrame {
final private int TOTAL_ROW = 3;
final private int TOTAL_COLUMN = 1;
TotalRowExample() {
super( "Total Row Example" );

final DecimalFormat formatter = new DecimalFormat("###,##0.00");
DefaultTableModel dm = new DefaultTableModel() {
public void setValueAt(Object value, int row, int col) {
Vector rowVector = (Vector)dataVector.elementAt(row);
if (col == TOTAL_COLUMN) {
Double d = null;
if (value instanceof Double) {
d = (Double)value;
} else {
try {
d = new Double(
((Number)formatter.parse((String)value)).doubleValue());
} catch (ParseException ex) {
d = new Double(0.0);
}
}
rowVector.setElementAt(d, col);
} else {
rowVector.setElementAt(value, col);
}
}

public boolean isCellEditable(int row, int col) {
if (row == TOTAL_ROW) return false;
return true;
}

public Class getColumnClass(int col) {
if (col == TOTAL_COLUMN) return Number.class;
return String.class;
}
};

dm.setDataVector(
new Object[][]{
{"coffee",new Double(0.0)},
{"tea" ,new Double(0.0)},
{"cocoa" ,new Double(0.0)},
{"total" ,new Double(0.0)}},
new Object[]{"Item","Price"});

JTable table = new JTable( dm ) {
public void editingStopped(ChangeEvent e) {
super.editingStopped(e);
reCalcurate(getModel());
repaint();
}
};

table.getColumn("Price").setCellRenderer(
new DecimalRenderer(formatter));

JScrollPane scroll = new JScrollPane(table);
Container content = getContentPane();
content.add(scroll);
setSize( 300, 120 );
setVisible(true);
}

private void reCalcurate(TableModel ml) {
if (ml == null) return;
double total = 0.0;
for (int i=0;i<TOTAL_ROW;i++) {
total += ((Double)ml.getValueAt(i,TOTAL_COLUMN)).doubleValue();
}
ml.setValueAt(new Double(total),TOTAL_ROW,TOTAL_COLUMN);
}

public static void main(String[] args) {
TotalRowExample frame = new TotalRowExample();
frame.addWindowListener( new WindowAdapter() {
public void windowClosing( WindowEvent e ) {
System.exit(0);
}
});
}
}

Sorting the table
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import java.text.*;
import javax.swing.*;
import javax.swing.table.*; public class SortableTableExample extends JPanel {
public SortableTableExample(){
setLayout(new BorderLayout());
String[] headerStr = {"Name","Date","Size","Dir"};
int[] columnWidth = {100,150,100,50};

SortableTableModel dm = new SortableTableModel() {
public Class getColumnClass(int col) {
switch (col) {
case 0: return String.class;
case 1: return Date.class;
case 2: return Integer.class;
case 3: return Boolean.class;
default: return Object.class;
}
}
public boolean isCellEditable(int row, int col) {
switch (col) {
case 1: return false;
default: return true;
}
}
public void setValueAt(Object obj, int row, int col) {
switch (col) {
case 2: super.setValueAt(new Integer(obj.toString()), row, col); return;
default: super.setValueAt(obj, row, col); return;
}
}
};
dm.setDataVector(new Object[][]{
{"b" ,getDate("98/12/02"),new Integer(14),new Boolean(false)},
{"a" ,getDate("99/01/01"),new Integer(67),new Boolean(false)},
{"d" ,getDate("99/02/11"),new Integer(2) ,new Boolean(false)},
{"c" ,getDate("99/02/27"),new Integer(7) ,new Boolean(false)},
{"foo" ,new Date() ,new Integer(5) ,new Boolean(true)},
{"bar" ,new Date() ,new Integer(10),new Boolean(true)}},
headerStr);

JTable table = new JTable(dm);
//table.setShowGrid(false);
table.setShowVerticalLines(true);
table.setShowHorizontalLines(false);
SortButtonRenderer renderer = new SortButtonRenderer();
TableColumnModel model = table.getColumnModel();
int n = headerStr.length;
for (int i=0;i<n;i++) {
model.getColumn(i).setHeaderRenderer(renderer);
model.getColumn(i).setPreferredWidth(columnWidth[i]);
}

JTableHeader header = table.getTableHeader();
header.addMouseListener(new HeaderListener(header,renderer));
JScrollPane pane = new JScrollPane(table);
add(pane, BorderLayout.CENTER);
}

public static void main(String[] args) {
JFrame f= new JFrame("SortableTable Example");
f.getContentPane().add(new SortableTableExample(), BorderLayout.CENTER);
f.setSize(400, 160);
f.setVisible(true);
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {System.exit(0);}
});
}

private static DateFormat dateFormat =
DateFormat.getDateInstance(DateFormat.SHORT, Locale.JAPAN);

private static Date getDate(String dateString) {
Date date = null;
try {
date = dateFormat.parse(dateString);
} catch(ParseException ex) {
date = new Date();
}
return date;
}

class HeaderListener extends MouseAdapter {
JTableHeader header;
SortButtonRenderer renderer;

HeaderListener(JTableHeader header,SortButtonRenderer renderer) {
this.header = header;
this.renderer = renderer;
}

public void mousePressed(MouseEvent e) {
int col = header.columnAtPoint(e.getPoint());
int sortCol = header.getTable().convertColumnIndexToModel(col);
renderer.setPressedColumn(col);
renderer.setSelectedColumn(col);
header.repaint();

if (header.getTable().isEditing()) {
header.getTable().getCellEditor().stopCellEditing();
}

boolean isAscent;
if (SortButtonRenderer.DOWN == renderer.getState(col)) {
isAscent = true;
} else {
isAscent = false;
}
((SortableTableModel)header.getTable().getModel())
.sortByColumn(sortCol, isAscent);
}

public void mouseReleased(MouseEvent e) {
int col = header.columnAtPoint(e.getPoint());
renderer.setPressedColumn(-1); // clear
header.repaint();
}
}
}

Use different fonts in different cells
// File: MultiFontCellTableExample.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
import javax.swing.border.*;

import jp.gr.java_conf.tame.swing.table.*;
public class MultiFontCellTableExample extends JFrame {

public MultiFontCellTableExample() {
super( "Multi-Font Cell Example" );

AttributiveCellTableModel ml = new AttributiveCellTableModel(8,3);
CellFont cellAtt =(CellFont)ml.getCellAttribute();
JTable table = new JTable( ml );
table.setRowHeight(26);
table.setCellSelectionEnabled(true);
table.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION);
table.setDefaultRenderer(Object.class ,new AttributiveCellRenderer());
JScrollPane scroll = new JScrollPane( table );

FontPanel fontPanel = new FontPanel(table, cellAtt);

Box box = new Box(BoxLayout.X_AXIS);
box.add(scroll);
box.add(new JSeparator(SwingConstants.HORIZONTAL));
box.add(fontPanel);
getContentPane().add( box );
setSize( 400, 200 );
setVisible(true);
}

class FontPanel extends JPanel {
String[] str_size = {"10","12","14","16","20","24"};
String[] str_style = {"PLAIN","BOLD","ITALIC"};
JComboBox name,style,size;

FontPanel(final JTable table, final CellFont cellAtt) {
setLayout(new BoxLayout(this,BoxLayout.Y_AXIS));
Box box = new Box(BoxLayout.X_AXIS);
JPanel p2 = new JPanel(new GridLayout(3,1));
JPanel p3 = new JPanel(new GridLayout(3,1));
JPanel p4 = new JPanel(new FlowLayout());
p2.add(new JLabel("Name:"));
p2.add(new JLabel("Style:"));
p2.add(new JLabel("Size:"));
Toolkit toolkit = Toolkit.getDefaultToolkit();
name = new JComboBox(toolkit.getFontList());
style = new JComboBox(str_style);
size = new JComboBox(str_size);
size.setEditable(true);
JButton b_apply = new JButton("Apply");
b_apply.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int[] columns = table.getSelectedColumns();
int[] rows = table.getSelectedRows();
if ((rows == null) || (columns == null)) return;
if ((rows.length<1)||(columns.length<1)) return;
Font font = new Font((String)name.getSelectedItem(),
style.getSelectedIndex(),
Integer.parseInt((String)size.getSelectedItem()));
cellAtt.setFont(font, rows, columns);
table.clearSelection();
table.revalidate();
table.repaint();
}
});
p3.add(name);
p3.add(style);
p3.add(size);
p4.add(b_apply);
box.add(p2);
box.add(p3);
add(box);
add(p4);
}
}

public static void main(String[] args) {
MultiFontCellTableExample frame = new MultiFontCellTableExample();
frame.addWindowListener( new WindowAdapter() {
public void windowClosing( WindowEvent e ) {
System.exit(0);
}
});
}
}

Display any JComponent in a cell
// File: Table.java
import java.awt.*;
import java.util.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;

public class Table
{
public static void main(String[] args)
{
JFrame frame = new JFrame("Table");
frame.addWindowListener( new WindowAdapter() {
public void windowClosing(WindowEvent e)
{
Window win = e.getWindow();
win.setVisible(false);
win.dispose();
System.exit(0);
}
} );

JTable table = new JTable( 6,4 )
{
public TableCellRenderer getCellRenderer(int row, int column) {
TableColumn tableColumn = getColumnModel().getColumn(column);
TableCellRenderer renderer = tableColumn.getCellRenderer();
if (renderer == null) {
Class c = getColumnClass(column);
if( c.equals(Object.class) )
{
Object o = getValueAt(row,column);
if( o != null )
c = getValueAt(row,column).getClass();
}
renderer = getDefaultRenderer(c);
}
return renderer;
}

public TableCellEditor getCellEditor(int row, int column) {
TableColumn tableColumn = getColumnModel().getColumn(column);
TableCellEditor editor = tableColumn.getCellEditor();
if (editor == null) {
Class c = getColumnClass(column);
if( c.equals(Object.class) )
{
Object o = getValueAt(row,column);
if( o != null )
c = getValueAt(row,column).getClass();
}
editor = getDefaultEditor(c);
}
return editor;
}

};

// Buttons
table.setValueAt( new JButton("Button"), 0, 0 );
table.setValueAt( new JButton("Button"), 0, 1 );


// Combobox
JComboBox combo = new JComboBox( new String[] {"First", "Second", "Third"} );
table.setValueAt( combo, 1, 1 );

// Labels
table.setValueAt( new JLabel("Label"), 1, 0 );
JLabel label = new JLabel( "Label", new ImageIcon( table.getClass().getResource("new.gif") ),
JLabel.LEFT);
table.setValueAt( label, 1, 2 );

// Scrollbar
table.setValueAt( new JScrollBar(JScrollBar.HORIZONTAL), 2,1 );

// RadioButtons
JRadioButton b1 = new JRadioButton( "Group1 Button1" );
JRadioButton b2 = new JRadioButton( "Group1 Button2" );
JRadioButton b3 = new JRadioButton( "Group1 Button3" );

ButtonGroup g1 = new ButtonGroup();
g1.add( b1 );
g1.add( b2 );
g1.add( b3 );

table.setValueAt( b1, 3, 0 );
table.setValueAt( b2, 3, 1 );
table.setValueAt( b3, 3, 2 );

table.setDefaultRenderer( JComponent.class, new JComponentCellRenderer() );
table.setDefaultEditor( JComponent.class, new JComponentCellEditor() );
JScrollPane sp = new JScrollPane(table);


frame.getContentPane().add( sp );
frame.pack();
frame.show();
}
}

class JComponentCellRenderer implements TableCellRenderer
{
public Component getTableCellRendererComponent(JTable table, Object value,
boolean isSelected, boolean hasFocus, int row, int column) {
return (JComponent)value;
}
}

// File: JComponentCellEditor.java
import java.awt.Component;
import java.awt.event.*;
import java.awt.AWTEvent;
import java.lang.Boolean;
import javax.swing.table.*;
import javax.swing.event.*;
import java.util.EventObject;
import javax.swing.tree.*;
import java.io.Serializable;
import javax.swing.*;

public class JComponentCellEditor implements TableCellEditor, TreeCellEditor,
Serializable {

protected EventListenerList listenerList = new EventListenerList();
transient protected ChangeEvent changeEvent = null;

protected JComponent editorComponent = null;
protected JComponent container = null; // Can be tree or table


public Component getComponent() {
return editorComponent;
}


public Object getCellEditorValue() {
return editorComponent;
}

public boolean isCellEditable(EventObject anEvent) {
return true;
}

public boolean shouldSelectCell(EventObject anEvent) {
if( editorComponent != null && anEvent instanceof MouseEvent
&& ((MouseEvent)anEvent).getID() == MouseEvent.MOUSE_PRESSED )
{
Component dispatchComponent = SwingUtilities.getDeepestComponentAt(editorComponent, 3, 3 );
MouseEvent e = (MouseEvent)anEvent;
MouseEvent e2 = new MouseEvent( dispatchComponent, MouseEvent.MOUSE_RELEASED,
e.getWhen() + 100000, e.getModifiers(), 3, 3, e.getClickCount(),
e.isPopupTrigger() );
dispatchComponent.dispatchEvent(e2);
e2 = new MouseEvent( dispatchComponent, MouseEvent.MOUSE_CLICKED,
e.getWhen() + 100001, e.getModifiers(), 3, 3, 1,
e.isPopupTrigger() );
dispatchComponent.dispatchEvent(e2);
}
return false;
}

public boolean stopCellEditing() {
fireEditingStopped();
return true;
}

public void cancelCellEditing() {
fireEditingCanceled();
}

public void addCellEditorListener(CellEditorListener l) {
listenerList.add(CellEditorListener.class, l);
}

public void removeCellEditorListener(CellEditorListener l) {
listenerList.remove(CellEditorListener.class, l);
}

protected void fireEditingStopped() {
Object[] listeners = listenerList.getListenerList();
// Process the listeners last to first, notifying
// those that are interested in this event
for (int i = listeners.length-2; i>=0; i-=2) {
if (listeners[i]==CellEditorListener.class) {
// Lazily create the event:
if (changeEvent == null)
changeEvent = new ChangeEvent(this);
((CellEditorListener)listeners[i+1]).editingStopped(changeEvent);
}
}
}

protected void fireEditingCanceled() {
// Guaranteed to return a non-null array
Object[] listeners = listenerList.getListenerList();
// Process the listeners last to first, notifying
// those that are interested in this event
for (int i = listeners.length-2; i>=0; i-=2) {
if (listeners[i]==CellEditorListener.class) {
// Lazily create the event:
if (changeEvent == null)
changeEvent = new ChangeEvent(this);
((CellEditorListener)listeners[i+1]).editingCanceled(changeEvent);
}
}
}

// implements javax.swing.tree.TreeCellEditor
public Component getTreeCellEditorComponent(JTree tree, Object value,
boolean isSelected, boolean expanded, boolean leaf, int row) {
String stringValue = tree.convertValueToText(value, isSelected,
expanded, leaf, row, false);

editorComponent = (JComponent)value;
container = tree;
return editorComponent;
}

// implements javax.swing.table.TableCellEditor
public Component getTableCellEditorComponent(JTable table, Object value,
boolean isSelected, int row, int column) {

editorComponent = (JComponent)value;
container = table;
return editorComponent;
}

}

ASCII Value Table