Adicionar ou atualizar um Objeto ArrayList

final ArrayList<Trackers> trackersList = new ArrayList<>();

Trackers trackers = new Trackers();
trackers.setSn(codRastreador);

if(trackersList.contains(trackers)){
      trackersList.remove(trackers);
      trackers.setAddress(ipClient);
      trackers.setPort(portClient);
      trackers.setTime(Calendar.getInstance());
      trackersList.add(trackers);
}
else{
      trackers.setAddress(ipClient);
      trackers.setPort(portClient);
      trackers.setTime(Calendar.getInstance());
      trackersList.add(trackers);
}

for(Trackers track : trackersList){
       if(trackers.getSn().equals(track.getSn())){
               trackersList.remove(trackers);
               trackers.setAddress(ipClient);
               trackers.setPort(portClient);
               trackers.setTime(Calendar.getInstance());
               trackersList.add(trackers);
      }
      else{
               trackers.setAddress(ipClient);
               trackers.setPort(portClient);
               trackers.setTime(Calendar.getInstance());
               trackersList.add(trackers);
      }
}