code: public void onClickCheckable(@NonNull View view, @NonNull CheckableViewHolder viewHolder) {
          if (isDir(viewHolder.file)) {
              goToDir(viewHolder.file);
          } else {
              onLongClickCheckable(view, viewHolder);
              if (singleClick) {
                  onClickOk(view);
              }
          }
      }
docs: Called when a selectable item is clicked. This might be either a file or a directory.
  
  @param view       that was clicked. Not used in default implementation.
  @param viewHolder for the clicked view