Subclassing JTextArea, but i cannot make it scroll

Question

The origin of my problem was that i wanted to make a text editor with a linecount on the left. I found a class on the internet which subclassed jpanel and added a scrollpane and a jtextpane into the panel, and overrid the paint() method in the JTextPane. I changed it to inherit from jtextarea to avoid rewriting all of the methods for editing and getting info from the JTextArea. It seems to work just fine, except for the scrolling, which i cannot get to work at all..
The new class is pasted here: http://pastebin.com/m236b79c9
And the clientclass is here: http://pastebin.com/m2f8199db
I can see three posible solutions:
1. make it work something like the way i have tried before. Perhaps the methods from Scrollable messes it all up?
2. I go back to a previous version where JPanel was the superclass, and write the methods i need to edit and get info from the JTextArea
3. Like #2, except I keep the JTextArea public and access it when needed for, and only write the methods that will be used the most.
#1 is preferable, if not, #2 or #3 is ok..
Gratefull for all help!

Answer 1

Ok, I merged the two classes above to make it small..
The code is here:
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.Point;
import javax.accessibility.AccessibleContext;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTabbedPane;
import javax.swing.JTextArea;
import javax.swing.text.Document;
import javax.swing.text.BadLocationException;
* @author Torstein
* @author Daniel Sjöblom
public class JNumberedTextArea2 extends JTextArea {
    private final static String uiClassID = "NumberedTextArea2UI";
    JScrollPane scrollPane;
    public JNumberedTextArea2() {
        this(null, null);
     * Constructs a new <code>JNumberedTextArea</code> with the text in
     * the JTextArea
     * @param text the text is added to the JTextArea
    public JNumberedTextArea2(String text, JScrollPane scrollPane) {
        super(text);
        setMinimumSize(new Dimension(30, 30));
        setPreferredSize(new Dimension(30, 30));
        setMinimumSize(new Dimension(30, 30));
        this.scrollPane = scrollPane;
    @Override
    public void paint(Graphics g) {
        super.paint(g);
        int charWidth = g.getFontMetrics(this.getFont()).charWidth('0');
        int antDigits = (int) Math.log10(this.getLineCount()) + 1;
        Insets margin = this.getMargin();
        margin.left = (charWidth * antDigits + 3);
        margin.top = 0;
        this.setMargin(margin);
        int start = this.viewToModel(scrollPane.getViewport().getViewPosition());
        int end = this.viewToModel(new Point(
                scrollPane.getViewport().getViewPosition().x + this.getWidth(),
                scrollPane.getViewport().getViewPosition().y + this.getHeight()
        Document doc = this.getDocument();
        int startline = doc.getDefaultRootElement().getElementIndex(start) + 1;
        int endline = doc.getDefaultRootElement().getElementIndex(end) + 1;
        int fontheight = g.getFontMetrics(this.getFont()).getHeight();
        int fontdesc = g.getFontMetrics(this.getFont()).getDescent();
        int starting_y = -1;
        try {
            starting_y = this.modelToView(start).y -
                    scrollPane.getViewport().getViewPosition().y + fontheight - fontdesc;
        } catch(BadLocationException e1) {
            e1.printStackTrace();
        for(int line = startline, y = starting_y; line <= endline; y += fontheight, line++) {
            g.drawString(Integer.toString(line) + ":", 0, y);
        this.repaint();
    public static void main(String[] args) {
      JFrame frame = new JFrame("JNumberedTextArea2");
      Container contPane = frame.getContentPane();
      JTabbedPane tabbedPane = new JTabbedPane();
      JScrollPane scrollPane = new JScrollPane();
      JNumberedTextArea2 textArea = new JNumberedTextArea2("This is a string\nit contains several lines\nindeed", scrollPane);
      scrollPane.setViewportView(textArea);
      tabbedPane.addTab("textArea", scrollPane);
      contPane.add(tabbedPane);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.pack();
      frame.setSize(new Dimension(400, 400));
      frame.setVisible(true);
}