[android] findViewByID returns null

In my particular case, I was trying to add a footer to a ListView. The following call in onCreate() was returning null.

TextView footerView = (TextView) placesListView.findViewById(R.id.footer);

Changing this to inflate the footer view instead of finding it by ID solved this issue.

View footerView = ((LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(R.layout.footer_view, null, false);