我正在开发一个springrestapi，由于某种原因，它不断返回nullreferenceexception。我不明白为什么。这是我的密码：
接口：

public interface InitiativesService {
    InitiativeDto createInitiative(InitiativeDto initiativeDto);    
}

实现它的类：

public class InitiativeServiceImpl implements InitiativesService {

    private final InitiativeRepository initiativeRepository;

    @Autowired
    public InitiativeServiceImpl(InitiativeRepository initiativeRepository)
    {
        this.initiativeRepository = initiativeRepository;
    }

    @Override
    public InitiativeDto createInitiative(InitiativeDto initiativeDto) {
        initiativeRepository.Save(initiativeDto);
    }

用于与数据库通信的存储库类：

@Repository
public interface InitiativeRepository extends JpaRepository<Initiative, Long> {}

最后是控制器：

public class InitiativesController {

  private InitiativesService initiativesService;

  public InitiativesController(InitiativesService initiativesService) {
    this.initiativesService = initiativesService;
  }

  @PostMapping(produces = MediaType.APPLICATION_JSON_VALUE, consumes = MediaType.APPLICATION_JSON_VALUE)
  public ResponseEntity<InitiativeDto> createInitiative(@Valid @RequestBody InitiativeDto initiative) {

    log.info("Saving");
    InitiativeDto createdInitiative = initiativesService.createInitiative(initiative);
    return ResponseEntity.status(HttpStatus.CREATED).body(createdInitiative);
  }

当我尝试运行这个并通过postman进行测试时，它返回一个nullpointerexception。我调试它，我可以看到initiativesservice为空。我很困惑，因为我有相同的实现来创建用户，没有这个问题也可以正常工作。有人能看出我这里有什么问题吗？