When you add a fragment as a part of your activity layout, it lives in a ViewGroup inside the activity's view hierarchy and the fragment defines its own view layout. code example
Example: change fragment in android studio
// put the following code in onClickListner
// public void onClickListner(View view){
Navigation.findNavController(view).navigate(R.id.action_fromFragment_toFragment);
// action_fromFragment_toFragment is the id of transformatino, look in fragment map.
// }