how to handle nullPointerException

Question

public List<PostResponse> getAllPosts(Optional<Long> userId) {
    List<Post> list;
    if (userId.isPresent())
        list = postRepository.findByUserId(userId.get());

    list = postRepository.findAll();
    return list.stream().map(p -> {
        List<LikeResponse> likes = likeService.getAllLikesWithParam(Optional.ofNullable(null), Optional.of(p.getId()));
        return new PostResponse(p, likes);}).collect(Collectors.toList());
}



public List<LikeResponse> getAllLikesWithParam(Optional<Long> userId, Optional<Long> postId) {
    List<Like> list;
    if(userId.isPresent() && postId.isPresent()) {
        list = likeRepository.findByUserIdAndPostId(userId.get(), postId.get());
    }else if(userId.isPresent()) {
        list = likeRepository.findByUserId(userId.get());
    }else if(postId.isPresent()) {
        list = likeRepository.findByPostId(postId.get());
    }else
        list = likeRepository.findAll();
    return list.stream().map(like -> new LikeResponse(like)).collect(Collectors.toList());
}

i get error in getAllPosts on this row Optional.ofNullable(null) error is: java.lang.NullPointerException: null

Does this answer your question? [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — Jens, Aug 22 '22 at 18:32

score 0 · Accepted Answer · answered Aug 25 '22 at 08:53

0

I can't tell just from the pasted code but it seems likely that likeService is null.

Also I would recomend using Optional.empty() instead of Optional.ofNullable(null) but that does not seem to be the cause of the problem here.

answered Aug 25 '22 at 08:53

L. Schilling

79
8

how to handle nullPointerException

1 Answers1