title: Notify Activity in Android to refresh when data is updated
body: <p>I have a background Service which updates the database in an Android App.
  In the App this data is displayed, but I am having trouble finding a good way to trigger a refresh of the data.</p>
  
  <p>Initially I just refreshed each time a view resumed, but that doesn't work obviously if the data is updated while the view is shown.</p>
  
  <p>On iOS I use notifications, which I register in the view, and is triggered by the update process when completed. Is there a way to do something similar in Android to trigger an update on the UI thread from a background thread? </p>