带Querydsl的Spring:Null指针异常

我正在尝试实现搜索过滤器功能和加载网格 spring boot data JPA 应用程序。用于创建我正在使用的动态查询 Querydsl .

1. 如果我经过sFloor,nBuildId只有匹配的记录应该显示在网格中

2. 如果我没有传递任何值,那么网格应该加载所有值。

null pointer exception .

房间控制器

@GetMapping("/getUnclaimedRoomDetails")
public List<Tuple> populateUnclaimedRoomGridView(@RequestParam(value="nBuildId", required=false) Integer nBuildId,
                                                 @RequestParam(value="sFloor", required=false) String sFloor) {
    return roomService.loadUnclamiedRoomGrid(nBuildId,sFloor);

}

客房服务

public  List<Tuple> loadUnclamiedRoomGrid(Integer nBuildId, String sFloor) {

    QRoom room = QRoom.room;        
    QRoomDepartmentMapping roomDepartmentMapping = QRoomDepartmentMapping.roomDepartmentMapping;

    JPAQuery<Tuple> query = new JPAQuery<Tuple>(em);

    query.from(room) 
         .where(room.nRoomId.notIn
                     (JPAExpressions.select(roomDepartmentMapping.nRoomId)
                           .from(roomDepartmentMapping)
                     )
           );

    if (nBuildId != 0) {
        query.where(room.nBuildId.eq(nBuildId));
    }

    if(sFloor != null) {
        query.where(room.sFloor.eq(sFloor));
    }       

return query.fetch();   

}

有谁能告诉我为什么我得到空指针异常而不是所有数据?