forse no
codice:
void deleteDir(String dir, String start, String end) {
  File d = new File(dir);
  File[] files = d.listFiles();
  for (File f : files) {
    String name = f.getName();
    if (name.startsWith(start) && name.endsWith(end))
      f.delete();
  }
}
deleteDir("path della dir", "ciao", ".txt");