Handling Type Erasure implementing Generics in Java 11 and Spring Boot
I'm refactoring my project and I'm sure I'm missing something obvious here, but I've been struggling with this for a few days now and could really use some help..... I'm working with a frustrating scenario with type erasure when using generics in a Spring Boot application. I'm trying to create a generic repository interface that works with various entity types. My goal is to ensure that the correct type is inferred at runtime, but I'm running into `ClassCastException` errors when I attempt to use my repository methods. Here’s a simplified version of my code: ```java public interface GenericRepository<T> { T findById(Long id); List<T> findAll(); } public class UserRepository implements GenericRepository<User> { @Override public User findById(Long id) { // Logic to retrieve a user by ID } @Override public List<User> findAll() { // Logic to retrieve all users } } public class ProductRepository implements GenericRepository<Product> { @Override public Product findById(Long id) { // Logic to retrieve a product by ID } @Override public List<Product> findAll() { // Logic to retrieve all products } } ``` When I call `findById` from my service layer, like this: ```java @Autowired private UserRepository userRepository; public User getUser(Long id) { return userRepository.findById(id); } ``` I occasionally receive a `ClassCastException` indicating that the object want to be cast to `User`. This seems to happen randomly, and I'm unsure why it's occurring since I’m following the generic type correctly. I have verified that my `UserRepository` is properly annotated with `@Repository` and that Spring is managing its lifecycle correctly. I've also checked for potential issues with my application context and tried different ways of injecting the repository, but nothing seems to alleviate the question. I'm using Java 11 with Spring Boot 2.5.4. Has anyone encountered similar issues with generics in Spring Boot? Are there known pitfalls related to type erasure that I should be aware of, or is there a more reliable pattern I should adopt for my repository implementation? I'm working on a application that needs to handle this. I'd really appreciate any guidance on this. I've been using Java for about a year now. What are your experiences with this? I'm developing on Linux with Java. Has anyone dealt with something similar? Cheers for any assistance!