👀 Views: 13 💬 Answers: 1 📅 Created: 2025-06-08

spring jpa hibernate classcastexception Java

I'm encountering a `ClassCastException` when trying to use a projection interface in a JPA query with Spring Data JPA. I'm using Spring Boot 2.5.4 and Hibernate 5.5.7. The projection interface is intended to only fetch specific fields from an entity, but when executing my repository method, I receive the following error: ``` java.lang.ClassCastException: com.example.User cannot be cast to com.example.UserProjection ``` Here's the projection interface I've defined: ```java public interface UserProjection { String getUsername(); String getEmail(); } ``` My entity looks like this: ```java @Entity public class User { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; private String username; private String email; // getters and setters } ``` And in my repository, I have the following method: ```java public interface UserRepository extends JpaRepository<User, Long> { List<UserProjection> findByActive(boolean active); } ``` When I call `userRepository.findByActive(true)`, it throws the `ClassCastException`. I've confirmed that there are users in the database that match the `active` status, and I've also double-checked the configuration of my JPA setup. I've tried using `@Query` with a native SQL query to see if it changes the behavior, but it resulted in a similar error: ```java @Query("SELECT username, email FROM users WHERE active = ?1") List<UserProjection> findActiveUsers(boolean active); ``` What could be causing this issue? Is there something I'm missing regarding projections in Spring Data JPA? Any insights would be greatly appreciated! For context: I'm using Java on Ubuntu 22.04. Thanks, I really appreciate it!