@Override
 public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
   super.onViewCreated(view, savedInstanceState);
   mBreadcrumbs = (PathBreadcrumbs) view.findViewById(R.id.breadcrumbs);
   mBreadcrumbs.setCallback(this);
   updateBreadcrumbs();
   addFragmentForTopOfStack();
 }
 private void updateBreadcrumbs() {
   String path = mDirStack.peek();
   mBreadcrumbs.setPath(path);
 }