👀 Views: 413 💬 Answers: 1 📅 Created: 2025-06-06

spring-boot jpa hibernate lazy-loading Java

I'm optimizing some code but I'm working on a project and hit a roadblock. This might be a silly question, but I'm currently working on a Spring Boot 2.6.0 application using JPA, and I've encountered a `NullPointerException` when trying to access a lazily loaded collection... I've set up a one-to-many relationship between `User` and `Post`. The `User` class has a `List<Post>` annotated with `@OneToMany(fetch = FetchType.LAZY)`. While fetching the user from the database, I noticed that if the `User` is not fully initialized, any attempt to access the `posts` collection results in a `NullPointerException`. Here is how I've defined my entities: ```java @Entity public class User { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; private String username; @OneToMany(mappedBy = "user", fetch = FetchType.LAZY) private List<Post> posts; } @Entity public class Post { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; private String content; @ManyToOne @JoinColumn(name = "user_id") private User user; } ``` I’m fetching a user like this: ```java User user = userRepository.findById(userId).orElse(null); ``` Then I attempt to access the posts: ```java List<Post> userPosts = user.getPosts(); ``` If the user has no posts, `user.getPosts()` returns `null`, and I end up with a `NullPointerException` when I try to iterate over `userPosts`. I have tried using `Optional.ofNullable(user.getPosts()).orElse(Collections.emptyList())` to prevent this, but I still need to ensure that the `posts` collection is initialized properly without running into performance issues or loading unnecessary data. Is there a proper way to handle this lazy loading scenario in Spring Boot with JPA? Any suggestions or best practices would be appreciated! What's the best practice here? I'm working with Java in a Docker container on Windows 11. Has anyone dealt with something similar? I'm on Ubuntu 20.04 using the latest version of Java.