Smart-tabbing help

Question

i am trying to implement a smart tabbing feature: when the user hits enter the smartTab function is called. textPane is a JTextPane.
       private void smartTab() {
            System.out.println("smartTab()");
                    //finds the last line
                      int carPos = textPane.getCaretPosition();
                      String str = textPane.getText().substring(0,carPos);
                      StringTokenizer st = new StringTokenizer(str,"\n");
                      String line = null;
                      for(int i=0; i<st.countTokens(); i++) {
                           if(!st.hasMoreElements()) break;
                           if(i==st.countTokens()-1) {
                                line = st.nextToken();
                                break;
                           } else {
                                st.nextToken();
                      int tabs = 0;
                      if(line==null) return;
                      for(int i=0; i<line.length(); i++) {
                           if(line.charAt(i)!='\t') break;
                           else tabs=i+1;
                      System.out.println("tabs calculated: "+tabs);
                      if(tabs==0) return;
                      String t = "";
                      for(int i=1; i<tabs; i++)
                           t = t+"\t";
                           try {
                                textPane.getDocument().insertString(carPos,t,null);
                           } catch(Exception e) {  }
                      System.out.println("tabs set");
            return;
       }sometimes it works, sometimes it doesn't.
Any help is greatly appreciated.
TravenE

Answer 1

I overrode the insertString(..) method of a Document to insert a matching brace "}" when a starting brace "{" is entered. Check out the code here if your interested:
www.discoverteenergy.com/files/SyntaxDocument.java
The concept for the "\n" character would be the same. Don't worry about the size of the class, most of the code is for syntax highlighting, the code you are interested in is only 10-15 lines.