code: public void deleteAll() {
          if(trackedFiles.size() == 0) {
              return;
          }
  
          ArrayList<File> files = new ArrayList<File>(trackedFiles);
          Collections.sort(files, filePathComparator);
  
          for(File file : files) {
              if(file.exists()) {
                  if(!file.delete()) {
                      throw new DataUtilException("Couldn't delete a tracked "
                              + (file.isFile()? "file":"directory" + ": ") + file.getAbsolutePath());
                  }
              }
          }
  
          trackedFiles.clear();
      }
docs: Delete all tracked files