Many times we want to force the user of our Android app to be updated, but the user ignore to update even when Google play store reminds to update. This video fairly deals with this problem.
If the app is already updated, it will show the current version, otherwise a pop-up with a button that says to update. When user click on update, it will open the Google play store, and hence user will do the update. If user click cancel, the application will be terminated.