JScrollPane.setRowHeaderView() and Row Numbers

Question

Hello there,
I am writing an editor using JEditorPane and am using JScrollPane's
setRowHeaderView() method to set row numbers. The code next shows how I am
doing it.
Now the problem is after I make a change in the editor, I am not able to see the
rownumbers from one even when I am at the top of the editorpane. But if I resize
the editorpane (which is in a frame) then I am able to see the row numbers from one.
Also, if I scroll up and down then the row numbers are seen properly from one. When the editor opens for the first time I am able to see the row numbers from the beginning i.e. one.
I think some where I am not calling revalidate(), validate(), or repaint()
properly. Please help. Thank you.
//method one
        //Rownumbers
        rowNums = new PreferenceJTextArea();
        rowNums.setEditable(false);
        rowNums.setMargin(new Insets(topMargin, 0, 0, 0));
        rowNums.setAlignmentX(Component.LEFT_ALIGNMENT);
        rowNums.setFont(myFont);
        int maxNumOfLines = setRowNums(displayFormat);
        rowNums.setBackground(Color.lightGray);
     mainScrollPane.setRowHeaderView(rowNums);
// end method one
//============================================================     
// method two
          public int setRowNums(int dispFormat) {
               StringBuffer str        = new StringBuffer();
               int          numOfLines = seq.getLineCount(dispFormat);
               for (int i = 1; i < (numOfLines + 1); i++) {
                    str = str.append(String.valueOf(i)).append("\n");
               rowNums.setText(str.toString());
               rowNums.validate();                         
               rowNums.revalidate();
               rowNums.repaint();
               return numOfLines;
// end method two
//============================================================     
// after making an editing change method three is called.
// method three           
               setRowNums(displayFormat); // this is where the text in the textarea gets
                                                                        // changed and causes unwanted results
               mainScrollPane.validate();
               mainScrollPane.revalidate();
               this.validate();               
               this.repaint();
// end method three      

Answer 1

Hello,
I have few questions regarding the proposed solutions.
1) In my application there is word wrapping, i.e. I am manually wrapping the text and not Java's inherent functionality.
2) There will be cases when the font size will be changed for the entire application. Though for a given document the font size will remain same.
3) Most of the time the application will be opening an existing files.
Hence, my question is will the proposed solutions still work. Also there is an overlap in the sense the solution using ViewFactory and EditorKit.
Pl do let me know if you have any idea wrt to any of the concerns posted here.
Thanks once again.
ac