How to give styles to my HTMLDocument inside a JTextPane?

Question

I have a JTextPane with a HTMLDocument attached to it. How can I style the text which is typed in? For example I want to set a larger font. How can I do this in my example?
Another problem is that when I hit the alignment buttons the text is actually aligned according to the hit button but the JEditorPane doesn't show the text correctly. It also doesn't enter a line feed when typing ENTER key.
Can someone help me on this please?
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextPane;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.text.BadLocationException;
import javax.swing.text.html.HTMLDocument;
import javax.swing.text.html.HTMLEditorKit;
public class AdditionalText extends JFrame implements ActionListener {
     private JButton leftAlign;
     private JButton centerAlign;
     private JButton rightAlign;
     private JTextPane editor;
     private JButton save;
     private JButton dump;
     public AdditionalText() {
          setTitle("Test Frame");
          JPanel topToolbar = new JPanel();
          leftAlign = new JButton("Left");
          centerAlign = new JButton("Center");
          rightAlign = new JButton("Right");
          ActionListener alignLeft = new HTMLEditorKit.AlignmentAction("alignLeft", 0);
          ActionListener alignCenter = new HTMLEditorKit.AlignmentAction("alignCenter", 1);
          ActionListener alignRight = new HTMLEditorKit.AlignmentAction("alignRight", 2);
          leftAlign.addActionListener(alignLeft);
          centerAlign.addActionListener(alignCenter);
          rightAlign.addActionListener(alignRight);
          topToolbar.add(leftAlign);
          topToolbar.add(centerAlign);
          topToolbar.add(rightAlign);
          editor = createEditor();
          JPanel bottomToolbar = new JPanel();
          save = new JButton("Save");
          save.addActionListener(this);
          dump = new JButton("Dump");
          dump.addActionListener(this);
          bottomToolbar.add(save);
          bottomToolbar.add(dump);
          getContentPane().add(BorderLayout.NORTH, topToolbar);
          getContentPane().add(BorderLayout.CENTER, editor);
          getContentPane().add(BorderLayout.SOUTH, bottomToolbar);
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
          setSize(new Dimension(640, 480));
          setLocation((screenSize.width - 640) / 2, (screenSize.height - 480) / 2);
     private JTextPane createEditor() {
          JTextPane textPane = new JTextPane() {
               public void paintComponent(Graphics g) {
                    Graphics2D g2 = (Graphics2D) g;
                    g2.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
                    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
                    g2.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
                    g2.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
                    g2.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
                    g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);
                    g2.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
                    g2.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_NORMALIZE);
                    g2.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
                    super.paintComponent(g2);
          textPane.setEditorKit(new HTMLEditorKit());
          return textPane;
     public void actionPerformed(ActionEvent e) {
          HTMLDocument htmlDocument = (HTMLDocument) editor.getDocument();
          if(e.getSource() == save) {
               HTMLEditorKit kit = (HTMLEditorKit)editor.getEditorKitForContentType("text/html");
               try {
                    kit.write(System.out, htmlDocument, 0, htmlDocument.getLength());
               } catch (IOException ex) {
                    ex.printStackTrace();
               } catch (BadLocationException ex) {
                    ex.printStackTrace();
          } else if(e.getSource() == dump) {
               htmlDocument.dump(System.err);
     public static void main(String[] args) {
          try {
               UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
          } catch (ClassNotFoundException e) {
               e.printStackTrace();
          } catch (InstantiationException e) {
               e.printStackTrace();
          } catch (IllegalAccessException e) {
               e.printStackTrace();
          } catch (UnsupportedLookAndFeelException e) {
               e.printStackTrace();
          AdditionalText at = new AdditionalText();
          at.show();
}

Answer 1

I created a class that can be used to highlight Java source code. Most of the code is for handling multi line comments. If you just want it to highlight certain keywords then you can get rid of all that logic. In case your interested, the code can be downloaded from here:
http://www.discoverteenergy.com/files/SyntaxDocument.java