[Android] 현재 실행중인 액티비티 가져오기

void getRunActivity()   {
    ActivityManager activity_manager = (ActivityManager)getSystemService(Context.ACTIVITY_SERVICE);
    List<ActivityManager.RunningTaskInfo> task_info = activity_manager.getRunningTasks(9999);

    for(int i=0; i<task_info.size(); i++)
        Log.e("test", "[" + i + "] activity:" + task_info.get(i).topActivity.getPackageName() + " >> " + task_info.get(i).topActivity.getClassName());
}

이 이전에 manifest 추가

<uses-permission android:name="android.permission.GET_TASKS"/>