Updating the Line number on status bar.

Question

Hi all,
I have developed an editor using swing, however I have used the JTextpane class to display the text. I had did of trouble with features such as go to line as this class does not support methods such as getLineCount in the JTextArea class. However I over came this by writing the method shown below.
The problem is that I want to show the current line number on the status bar. When do I call this method? After every '\n'?
The setLine Number method is below.
Thanks for your help
Ciara
public void setLineNumber(int num) {
int lineNum = 1;
int lastNewline = 0;
char text[] = editor.getText().toCharArray();
if (num < 1)
return;
if (num == 1) {
editor.setCaretPosition(0);
return;
int i;
for (i = 0; i < text.length; i++) {
     if (text[i] == '\n') {
     lastNewline = i;
     lineNum++;
     if (num == lineNum) {
     editor.requestFocus();
     editor.setCaretPosition(lastNewline + 1);
     return;
}     

Answer 1

Perhaps extending a PlainDocument is better, if line
numbers are meaningful for your application.
About your method, mind that getText can be quite dear,
so it is better not to call it if you don't need it.
For a more efficient alternative, look at Document.getText(int offset, int length, Segment txt)It uses a Segment (un unguarded string) pointing directly
into the document, which you can use much like a char
array.
As to your question, I would define a CaretListener
so as to update the status bar when the caret moves.