What " doesn't work"?
(I wish to get 1 € each time I read this kind of vague problem description... )

Looks OK, except you return the unfiltered list. Not sure if that's what you want (ie. if you just want to printout the correct names) or if you want to build another list with only the file you want (use an ArrayList, for example).

LOL, you are right PhiLho, the description is a bit vague. I thought that by saying I want to get the filetypes from the list is why this code does not work. You can get of course the files of a folder, but the function does not return the "cleaning" that I try to do with the line:

Ok, now it works with a new arraylist

Yes, that's the spirit!
Here is a more encapsulated example (not relying on global variables):

1. ArrayList<String> listFileNames(String path) {
2.   ArrayList<String> result = new ArrayList<String>();
3.   File file = new File(path);
4.   if (file.isDirectory()) { 
5.     String names[] = file.list();
6.     for (String name : names) {
7.       if (name.toLowerCase().endsWith(".csv")) {
8.         result.add(name);
9.       }
10.     }
11.   }
12.   return result;
13. }

ArrayList<String> filenames = listFileNames(path);

Nice side effect: no need to check for null on return, you can iterate on filenames in all cases, it will be just an empty loop in file is not a directory.

Hello, i'm interesting by this code, so I try to use but I failed. Maybe something wrong in my code. When I use I receive something empty in my consol []. for information I change .csv by .jpg

1. String path = "/dataFolder";
   void setup(){
     println(listFileNames(path));
   }
   
   ArrayList<String> listFileNames(String path) {
     ArrayList<String> result = new ArrayList<String>();
     File file = new File(path);
     if (file.isDirectory()) {
       String names[] = file.list();
       for (String name : names) {
         if (name.toLowerCase().endsWith(".jpg")) {
           result.add(name);
         }
       }
     }
     return result;
   }

Makio135
http://makio135.com/

Yes. If you start a path with a slash, it means you make an absolute path relative to the current system root (eg. C: on Windows, or similar).

Mmm, actually, you should use:

1. void setup(){
2.   println(listFileNames(dataPath("dataFolder")));
3. }

(File is a Java class, it doesn't know about the data folder.)