How can I get an extension from a file...in JFileChooser

Question

I have got a problem here. Here I have a JFileChooser, I want to add in
a FileFilter, and user could only see some type of file. But as long as I
try to get the extension....It wont compile, could any one teach me how
to get the extension of a file in JFILECHOOSER???
============================================
import java.io.*;
import java.io.File.*;
import javax.swing.filechooser.FileFilter;
public class MainFrame extends JFrame implements ActionListener {
public MainFrame() {.............}
private boolean chooseFile()
JFileChooser fileChooser = new JFileChooser();
fileChooser.setFileSelectionMode( JFileChooser.FILES_ONLY );
FileChoser filtering = new FileChoser("txt");
fileChooser.setFileFilter(filtering);
fileChooser.addChoosableFileFilter(filtering);
int selection = fileChooser.showOpenDialog( this );
if ( selection == JFileChooser.CANCEL_OPTION )
return false;
if (selection == -1) {
return false;
File tmpfile = fileChooser.getSelectedFile();
filename = tmpfile.toString();
setTitle( "Smiggin Holes 2010 - " + filename );
return true;
static class FileChoser extends javax.swing.filechooser.FileFilter
String extension;
String description;
public FileChoser(String extension, String description){
this.extension = extension;
this.extension = description;
// Accept all directories and all gif, jpg, or tiff files.
public boolean accept(File f)
if (f != null)
if (f.isDirectory())
return true;
String ext = getExtension(f); //<<<<<<<<<<<THE PROBLEM IS HERE WHEN I TRY TO GET THE EXTENSION OF THE FILE. IT CANT COMPILE
System.out.println("aasdfasdf"+ext);
if ((ext!=null)&&(ext.equals(extension)))
return true;
return false;
// The description of this filter
public String getDescription() {
return "Just Text Files";
======================================
Could you tell me what can I do? To get the extension of the file selected by the user?
And What do I have to change?
Regards,

Answer 1

Hi,
can you post your compile error and the code of getExtension().
Regards
Ldinka