How to detect programmatically when other apps are closed / force stopped

How to detect programmatically when other apps are closed / force stopped

I am developing an android application in which i need to perform an
action when other apps are closed / force stopped. This detection has to
be made from a service which is been running in the background once
started. Making the service to run continuously is not a problem but
making detection when other apps are closed is the problem. Please do
anyone have any solution.....