ActivityManager.MemoryInfo memInfo = new ActivityManager.MemoryInfo();
ActivityManager activityManager = (ActivityManager) getActivity().getSystemService(Context.ACTIVITY_SERVICE);
activityManager.getMemoryInfo(memInfo);
String TotalRam = String.valueOf(memInfo.totalMem);
int totaLram = Integer.parseInt(TotalRam);
String freeRam = String.valueOf(memInfo.availMem);
int freRAm = Integer.parseInt(freeRam);

Handler handler = new Handler(Looper.getMainLooper());
Runnable myTask = new Runnable() {
  void run() {
    // do something ...

    handler.postDelayed(myTask, 100 /* milliseconds */);
  }
};

void onStart() {
  super.onStart();

  handler.post(myTask);
}

void onStop() {
  super.onStop();

  handler.removeCallbacks(myTask);
}