FragmentActivity: Cannot cast from Fragment to derived class

Question

I am trying to use a Fragment in a FragmentActivity like so:

TutViewerFragment viewer = (TutViewerFragment)    
getSupportFragmentManager().findFragmentById(R.id.tutview_fragment);

And my TutViewerFragment extends Fragment. However I am getting an error:

Cannot cast from Fragment to TutViewerFragment.

I really don't understand why this is happening. Why can't it be cast?

Answer 1

You are extending the wrong Fragment class. Import android.support.v4.app.Fragment instead of android.app.Fragment.

Answer 2

As devconsole pointed out in the comment above: The class that extends Fragment needs to import

android.support.v4.app.Fragment;

and not

android.app.Fragment;

I guess it has to do with the Android Compatibility Package. Problem is now resolved!

Answer 3

Just in case people are looking for kotlin equivalent:

myFragmentClass = supportFragmentManager.findFragmentById(R.id.my_fragment) as MyFindOfFragment