Cursor issues in JTextarea

Hi,

I want to create an linux terminal like interface using java swing.The fllowing code i have written.But i'm facing issues while pressing arrow keys in textarea.Please run this code to understand the problem.

1. package poc.gui;
3. import java.awt.Color;
4. import java.awt.Graphics;
5. import java.awt.Rectangle;
7. import javax.swing.JFrame;
8. import javax.swing.JTextArea;
9. import javax.swing.plaf.TextUI;
10. import javax.swing.text.BadLocationException;
11. import javax.swing.text.DefaultCaret;
12. import javax.swing.text.JTextComponent;
14. public class CaretDemo extends JFrame
15. {
16. JTextArea area=null;
17. CaretDemo()
18. {
19. setSize(400,400);
20. area = new JTextArea();
21. area.setCaret(new NewCaret());
22. add(area);
23. }
24. public static void main(String[] args) {
25. // TODO Auto-generated method stub
26. CaretDemo dc = new CaretDemo();
27. dc.setVisible(true);
28. }
29. }
30. class NewCaret extends DefaultCaret
31. {
32. protected void damage(Rectangle r)
33. {
34. //System.out.println("damage : x="+x+", y="+y+", height="+height+", width="+width+", dot="+getDot()+", mark="+getMark());
35. //super.damage(r);
36. if(r!=null)
37. getComponent().repaint(r.x,r.y,8,r.height);
38. }
39. public void paint(Graphics g)
40. {
41. //super.paint(g);
42. g.setColor(Color.GREEN);
43. JTextComponent comp = getComponent();
44. Rectangle rec = null;
45. TextUI ui = comp.getUI();
46. try {
47. rec = ui.modelToView(comp, getDot());
48. } catch (BadLocationException e) {
49. // TODO Auto-generated catch block
50. e.printStackTrace();
51. }
52. g.fillRect(rec.x, rec.y, 8, rec.height);
53. }
54. } //Help is expected