java - 调用另一个类方法时出现空指针异常

Question

我正在使用 spring data jpa 来创建服务。 当我独立检查方法的结果时，我试图调用 Room Department Mapping类方法，它工作正常。但是当我从客房服务类调用这个方法时，我正在 进入Room service.unclaimedRoomAssign()java.lang.NullPointerExceptionRoomDepartmentMappingController

rdmService对象参考我得到空，但我不明白为什么那个参考是空的？谁能告诉我？

RoomDepartmentMappingController 类

public class RoomDepartmentMappingController {

    @Autowired
    RoomDepartmentMappingService rdmService;

    @PostMapping("/assignUnclaimedRooms")
    public ResponseEntity<String> unclaimedRoomAssign(@NotNull  @RequestParam(name="nDeptId", required= true) Integer nDeptId,
                                                      @NotNull  @RequestParam(name="nRoomId" , required = true) Integer nRoomId,
                                                      @Nullable @RequestParam(name="nSubDeptId" , required = false) Integer nSubDeptId){

        return ResponseEntity.ok(rdmService.unclaimedRoomAssign(nDeptId, nRoomId,nSubDeptId ));   //line no 29 rdmService object is getting null

}
}

RoomDepartmentMappingService 类

@Service
public class RoomDepartmentMappingService {

    @Autowired
    RoomDepartmentMappingRepository roomDepartmentmappingRepo;  

    //Assign Unclaimed room to specified department and sub department  
    public String unclaimedRoomAssign(Integer nDeptId, Integer nRoomId, Integer nSubDeptId) {

        RoomDepartmentMapping roomDepartmentMappingObj = new RoomDepartmentMapping();

        if(nDeptId != 0) {
        roomDepartmentMappingObj.nDeptId = nDeptId;
        roomDepartmentMappingObj.nRoomId = nRoomId;     

        roomDepartmentMappingObj.nSubdeptId= nSubDeptId;
        roomDepartmentMappingObj.nPercentageAssigned = 100;
        roomDepartmentMappingObj.sStatus = "R";

        }       
        roomDepartmentmappingRepo.save(roomDepartmentMappingObj);

        return "Room assign sucessfully";

    }

}

RoomDepartmentMappingRepository 类

@Repository
public interface RoomDepartmentMappingRepository extends JpaRepository<RoomDepartmentMapping, Integer>{


}

客房服务类

在这里，当我打电话时，rdmObj.unclaimedRoomAssign()我得到空指针异常

@Service
public class RoomService {

    @Autowired
    RoomRepository roomRepository;  

    // Add new Room Details
        public String addNewRoom(@RequestBody RoomInformation roomInfo) {           

            Room roomRecord = new Room();

            if(roomInfo.nCampusId != 0)
            roomRecord.nCampusId = roomInfo.nCampusId; 
            roomRecord.sRoomNumber=roomInfo.sRoomNumber;
            roomRecord.sRoomDesc=roomInfo.sRoomDesc;
            roomRecord.nArea=roomInfo.nArea;

            roomRepository.save(roomRecord);  // able to save data in room

            if (roomInfo.nDeptId !=0 && roomRecord.nRoomId !=0) {

                System.out.println("inside if");

                RoomDepartmentMappingController rdmObj= new RoomDepartmentMappingController();
                rdmObj.unclaimedRoomAssign( roomInfo.nDeptId, roomRecord.nRoomId, roomInfo.nSubDeptId); 

            }
            return "New room added sucessfully";
        }

安慰

inside if
2018-09-27 13:36:44.183 ERROR 11872 --- [nio-7075-exec-2] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause

java.lang.NullPointerException: null
    at com.spacestudy.controller.RoomDepartmentMappingController.unclaimedRoomAssign(RoomDepartmentMappingController.java:29) ~[classes/:na]
    at com.spacestudy.services.RoomService.addNewRoom(RoomService.java:113) ~[classes/:na]
    at com.spacestudy.controller.RoomController.addNewRoom(RoomController.java:41) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_144]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_144]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_144]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[na:1.8.0_144]

标签： javaspring-data-jpamethod-call