Spring with Querydsl : Null Pointer Exception

Question

I am trying to implement Search filter functionality and load grid in spring boot data JPA application. For creating dynamic query I am using Querydsl.

I am searching data according to sFloor and nBuildId.

If I am passing sFloor, nBuildId only that matching record should display in grid
If I am not passing any values then grid should load with all values.

I tried like below In that when I am passing data I am able to filter data. But when I am not passing any records I am getting null pointer exception.

RoomController

@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);

}

RoomService

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();   

}

Can any one please tell me why I am getting null pointer exception instead of all data?

On which line do you get the exception?

Jens Schauder
– Jens Schauder

2018-08-31 08:41:02 +00:00
Commented Aug 31, 2018 at 8:41 — Jens Schauder
– Jens Schauder, Commented Aug 31, 2018 at 8:41

Robert Bain · Accepted Answer · 2018-08-31 08:31:57Z

1

I think the issue is if (nBuildId != 0). nBuildId is a big Integer so when the check is being performed it is being unboxed to a primitive int. If it's null, this will cause a NullPointerException. A null check on nBuildId should fix things, E.G. if (nBuildId != null && nBuildId != 0).

answered Aug 31, 2018 at 8:31

Robert Bain

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4 Comments

SpringUser Over a year ago

its working properly Thank you. one more thing is I want particular column from Query Result. so How I can iterate this List<Tuple>

SpringUser Over a year ago

I tried by using for each loop but getting class cast exception ` List<Tuple> queryResult = query.fetch(); for(Tuple row : queryResult) { System.out.println("Build Id " +row.get(room.nBuildId)); }

Robert Bain Over a year ago

Raise a separate question as this is unrelated to the NullPointerException.

SpringUser Over a year ago

Ok. https://stackoverflow.com/questions/52114040/spring-with-querydsl-java-lang-classcastexception

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