I have a fragment I am trying to add into a view.
FragmentManager fragMgr=getSupportFragmentManager();
feed_parser_activity content = (feed_parser_activity)f
Just in case someone's made the same stupid mistake I did; check that you're not overwriting the activity content somewhere (i.e. look for additional calls to setContentView)
In my case, due to careless copy and pasting, I used DataBindingUtil.setContentView in my fragment, instead of DataBindingUtil.inflate, which messed up the state of the activity.