I found on the Web code: http://java-sl.com/tip_autoreplace_smiles.html which I edited to my own needs, take a look:
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.io.IOException;
import javax.swing.*;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.*;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
public class Emotes extends JEditorPane {
public Emotes() {
super();
this.setEditorKit(new StyledEditorKit());
this.initListener();
}
private void replace (String text, StyledDocument doc, ImageIcon icon, int start, String what) throws BadLocationException
{
int i = text.indexOf(what);
while(i >= 0)
{
final SimpleAttributeSet attrs = new SimpleAttributeSet(doc.getCharacterElement(start+i).getAttributes());
if (StyleConstants.getIcon(attrs) == null)
{
StyleConstants.setIcon(attrs, icon);
doc.remove(start+i, what.length());
doc.insertString(start+i,what, attrs);
}
i = text.indexOf(what, i+what.length());
}
}
private void initListener() {
getDocument().addDocumentListener(new DocumentListener(){
@Override
public void insertUpdate(DocumentEvent event) {
final DocumentEvent e=event;
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
if (e.getDocument() instanceof StyledDocument) {
try {
StyledDocument doc=(StyledDocument)e.getDocument();
int start= Utilities.getRowStart(Emotes.this,Math.max(0,e.getOffset()-1));
int end=Utilities.getWordStart(Emotes.this,e.getOffset()+e.getLength());
String text=doc.getText(start, end-start);
replace(text, doc, createEmoticon("wink.png"), start, ";)");
replace(text, doc, createEmoticon("wink.png"), start, "<wink>");
replace(text, doc, createEmoticon("sad.png"), start, ":(");
replace(text, doc, createEmoticon("sad.png"), start, "<sad>");
replace(text, doc, createEmoticon("smile.png"), start, ":)");
replace(text, doc, createEmoticon("smile.png"), start, "<smile>");
} catch (BadLocationException e1) {
e1.printStackTrace();
}
}
}
});
}
@Override
public void removeUpdate(DocumentEvent e) {
}
@Override
public void changedUpdate(DocumentEvent e) {
}
});
}
static ImageIcon createEmoticon(String icon)
{
BufferedImage img = null;
try
{
img = ImageIO.read(new File(icon));
Graphics g = img.getGraphics();
((Graphics2D)g).setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
}catch (IOException ex)
{
}
return new ImageIcon(img);
}
}
which works great. But I created in Netbeans a new GUI (JDialog Window) with JEditorPane on it, where I want to use this feature on JDialog window:
but it doesnt want to work at all. When I type ":)" its not changing in an image.
Just try to run that code:
public class NewJDialog extends javax.swing.JDialog {
/** Creates new form NewJDialog */
public NewJDialog(java.awt.Frame parent, boolean modal) {
super(parent, modal);
initComponents();
}
/** This method is called from within the constructor to
* initialize the form.
* WARNING: Do NOT modify this code. The content of this method is
* always regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jScrollPane1 = new javax.swing.JScrollPane();
jEditorPane1 = new Emotes();
setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);
jScrollPane1.setViewportView(jEditorPane1);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 400, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 376, Short.MAX_VALUE)
.addContainerGap()))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(51, 51, 51)
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 229, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(20, Short.MAX_VALUE)))
);
pack();
}// </editor-fold>
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(NewJDialog.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(NewJDialog.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(NewJDialog.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(NewJDialog.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the dialog */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
NewJDialog dialog = new NewJDialog(new javax.swing.JFrame(), true);
dialog.addWindowListener(new java.awt.event.WindowAdapter() {
@Override
public void windowClosing(java.awt.event.WindowEvent e) {
System.exit(0);
}
});
dialog.setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JEditorPane jEditorPane1;
private javax.swing.JScrollPane jScrollPane1;
// End of variables declaration
}
And the emotes I use are: 
