android listen for app launch

Question

I need to develop a service which listen for every activity start. Must I do something like this?

ActivityManager am = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
List<ActivityManager.RunningAppProcessInfo> runningAppProcessInfo = am.getRunningAppProcesses();
for (int i = 0; i < runningAppProcessInfo.size(); i++) {
    Log.v("Proc: ", runningAppProcessInfo.get(i).processName);
}

And do I need to do it every X seconds? Does it affect battery consumption?

Answer 1

As far as I know there is a class IActivityController.Stub in android.app package. But this is an {@hide} interface (as someone said there have some method to access @hide api).

We can set a Listener to listen Activity switch like this:

mAm = ActivityManagerNative.getDefault();          
    try {
        mAm.setActivityController(new ActivityController());

   } catch (RemoteException e) {
        System.err.println("** Failed talking with activity manager!");}

and Class ActivityManagerNative is @hide also. ActivityController is a class extends IActivityController.Stub .

How to access @hide Api:

1. you can get the android source code to build an have-@hide-api Android.jar to use.
2. by reflection.