Possible error with Google's Navigation Drawer tutorial

I'm following this Navigation Drawer Tutorial by Google which can be found here. http://ift.tt/19gZbZG

I having trouble with this line

    FragmentManager fragmentManager = getFragmentManager();

which says that getFragmentManger can't be resolve to a type. I did some research and I found that you getFragmentManager is a method of the Activity class., but in the tutorial the class in question is a DrawerItemClickListener which implements ListView.OnItemClickListener

Did I misinterpret something ?