FileDialog, how to set filter?

Question

i try to use
setFilenameFilter(FilenameFilter filter)
to set filter for FileDialog, but FilenameFilter is an interface, what is the story?
do u know how to set filter?
thanks in advance

Answer 1

Construct a FileFilter class like:
public class CustomFilter implements FileFilter{
     public CustomFilter(){
public String getFileExtension(File file) {
String ext = null;
String s = file.getName();
int i = s.lastIndexOf(".") + 1;
ext = s.substring(i).toLowerCase();
return ext;
public String doSomething(){
//do Something
//return something
and use the setFileFilter(FileFilter filter) method.