How to find out how many apps are running in the background in Android?

Question

I can run the application in the background, but I want to know how many applications are running in the background. Like on some mobile devices, pressing the center button displays a list of currently running applications.

Is this possible in android? If possible, give some code snippets and steps for this.

Answer 1

Dev Tools application (installed in emulators) shows a list of running processes, having received an ActivityManager instance:

 ActivityManager am = (ActivityManager)getSystemService(Context.ACTIVITY_SERVICE); List<ActivityManager.RunningAppProcessInfo> l = am.getRunningAppProcesses();