Android common functionality in activity

I have 10 activities in my app. Some activities inherit from FragmentActivity and some from AppCompatActivity. I want to implement some common functionality for all activities. E.g. I want to implement timeout functionality for all activites, i.e I want to display warning on screen when there is no user interaction during timeout period (= onUserInteraction not called during timeout period). What is the best way to achieve this? I want to minimize having the same code in my activites. The best would be to have no common code in my activities.