code: private File[] filenamesToFiles(String[] filenames) {
          if (filenames == null) {
              return null;
          }
          int count = filenames.length;
          File[] result = new File[count];
          for (int i = 0; i < count; ++i) {
              result[i] = new File(this, filenames[i]);
          }
          return result;
      }
docs: Converts a String[] containing filenames to a File[].
  Note that the filenames must not contain slashes.
  This method is to remove duplication in the implementation
  of File.list's overloads.