Spring move code from controller to service

I'm new to spring and will like move my working code from the controller to the service for best practice, but now I get a:

SEVERE: Servlet.service() for servlet [mvc-dispatcher] in context with path [/xls] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause java.lang.NullPointerException

MainController.java

public class MainController {
  private ListServiceImpl listServiceImpl;
    @RequestMapping(value = "/uploadFile", method = RequestMethod.POST)
     public ModelAndView upload(@RequestParam("myfile") MultipartFile myFile)  throws IOException {
    InputStream inputStream = myFile.getInputStream();
    ModelAndView model = new ModelAndView("list");
    model.addObject("list", listServiceImpl.getList(inputStream) );
  return model; 
}

ListServiceImpl.java

@Service
public class ListServiceImpl implements ListService {
  @Override
  public List<UserAndSum> getList(InputStream inputStream) {
  List <UserAndSum> list25plus25 = new ArrayList<UserAndSum>();
  Workbook workBook = Workbook.getWorkbook(inputStream);
  ..............
  list25plus25 .add(new UserAndSum(previousUser, sum));
return list25plus25;
}