Android remember fragment to back stack

Use following code to set current fragment to backstack and load new fragment

PdfFragment newFragment = new PdfFragment();

  Bundle args = new Bundle();
  args.putString("name", sub_category.name);
  args.putString("catId", String.valueOf(sub_category.id));
  args.putString("pdf_from", "sub_category");

  newFragment.setArguments(args);

  FragmentTransaction transaction = getSupportFragmentManager()
    .beginTransaction();

  // Replace whatever is in the fragment_container view with this
  // fragment,
  // and add the transaction to the back stack so the user can
  // navigate back
  transaction.setCustomAnimations(R.anim.left_to_right,
    R.anim.right_to_left);
  transaction.replace(R.id.fragment_container, newFragment);

// use following code to set current fragment to back stack and load new fragment
  transaction.addToBackStack(null);

  // Commit the transaction
  transaction.commit();