I am using spring data jpa for creating services. I am trying to call  Room Department Mapping class method in Room service.  When I am checking result of unclaimedRoomAssign() method independently its working properly. But When I am calling this method from Room Service class I  am getting    java.lang.NullPointerException in RoomDepartmentMappingController
rdmService object ref I am getting null but I am not getting why that ref is null? Can any one please tell me?
RoomDepartmentMappingController class
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 class
@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 class
@Repository
public interface RoomDepartmentMappingRepository extends JpaRepository<RoomDepartmentMapping, Integer>{
}
RoomService class
Here when I am calling rdmObj.unclaimedRoomAssign() I am getting null pointer exception
@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";
        }
Console
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]
