Hi. Try this. The ArrayList is typed on File class, but you can use whatever you want (ie. <String> if you only want to handle file names).

1. void setup(){
2.   ArrayList<File> filesList = filesToArrayList();
3.   for(File f : filesList){
4.     println(f.getName());
   
5.   }
   
6. }
   
7. ArrayList filesToArrayList() {
8.   ArrayList<File> filesList = new ArrayList<File>();
9.   String folderPath = selectFolder();
10.   if (folderPath != null) {
11.     File file = new File(folderPath);
12.     File[] files = file.listFiles();
13.     for (int i = 0; i < files.length; i++) {
14.       filesList.add(files[i]);
    
15.     }
    
16.   }
17.   return(filesList);
18. }
    
19. 
    

Wow! I had no idea about that method! Excellent!