Sort File List

File[] directoryList = currentFolder.listFiles(); 
if (directoryList != null) {
   List<File> directoryListing = new ArrayList<File>();
   directoryListing.addAll(Arrays.asList(directoryList));
   Collections.sort(directoryListing, new SortFileName());
   Collections.sort(directoryListing, new SortFolder());
}


//sorts based on the files name
public class SortFileName implements Comparator<File> {
    @Override
    public int compare(File f1, File f2) {
          return f1.getName().compareTo(f2.getName());
    }
}

//sorts based on a file or folder. folders will be listed first
public class SortFolder implements Comparator<File> {
    @Override
    public int compare(File f1, File f2) {
         if ((f1.isDirectory() && f2.isDirectory())
                || (!f1.isDirectory() && !f2.isDirectory()))
            return 0;
         else if (f1.isDirectory() && !f2.isDirectory())
            return -1;
         else
            return 1;
          }
}

public class SortFileDate implements Comparator<File> {

     @Override

     public int compare(File f1, File f2) {

      return Long.compare(f1.lastModified(), f2.lastModified());

     }

 }