import java.util.Arrays;
import java.util.Comparator;
import java.io.File;

void sortFilesWtihDescending(File[] files) {
  Arrays.sort(files, new Comparator<Object>() {
    public int compare(Object sa, Object sb) {
      File f1 = (File)sa;
      File f2 = (File)sb;
      if (f1.getName().charAt(0) < f2.getName().charAt(0)) {
        return 1;
      } else {
        return 0;
      }
    });
}

Sort a File array with the descending of file name.

sortFilesWithDescending(File [] files)

Java