title: How to detect/listen Android Application's / Activity's running changes from inside a service?
body: <p>I've running a Service. This service should listen (i.e. per BroadcastReceiver) for Activity/Application start/resume Action, whatever. My goal is to do something, everytime an application starts, or another application is started / resumed, in short, the current front application changes. How can I do this? </p>