How to Use Java Records with Spring Boot

 Introduction to Java record

Java 14 introduced the Java record feature (as a preview) and officially introduced it in Java 16. A Java record is a special class used to store immutable data.

📌 Key Features of Java record:
✔ Immutable fields – Cannot be modified after creation.
✔ Auto-generated constructor, getters, toString(), equals(), and hashCode().
✔ Ideal for DTOs, API responses, and data modeling.

Declaring a Simple record (Employee Example)

public record Employee(int id, String firstName, String lastName, String email) {}

📌 What this automatically generates:

// Equivalent traditional Java class
public final class Employee {
    private final int id;
    private final String firstName;
    private final String lastName;
    private final String email;

    public Employee(int id, String firstName, String lastName, String email) {
        this.id = id;
        this.firstName = firstName;
        this.lastName = lastName;
        this.email = email;
    }

    public int id() { return id; }
    public String firstName() { return firstName; }
    public String lastName() { return lastName; }
    public String email() { return email; }

    @Override
    public boolean equals(Object obj) { /* Auto-generated */ }
    @Override
    public int hashCode() { /* Auto-generated */ }
    @Override
    public String toString() { /* Auto-generated */ }
}

📌 Why record is better?
✅ No need to write constructors, getters, toString(), equals(), or hashCode().
✅ Immutable by default (No setters).

🔥 Why Use Records in Spring Boot?

✅ Common Use Cases in Spring Boot

Here are the best places to use records in a Spring Boot app:

Real-World Example: REST API with Java Records

Let’s build a simple Spring Boot app with a Product entity and a ProductDTO using record.

Step 1: Entity Class

@Entity
public class Product {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;
    private String description;
    private Double price;

    // Getters, Setters, Constructors (or use Lombok)
}

Step 2: DTO Using Record

public record ProductDTO(Long id, String name, String description, Double price) {}

This generates:

• A constructor with all fields
• getters (named as the fields)
• equals(), hashCode(), and toString()

🧠 Records are implicitly final and immutable.

✅ One line replaces 40+ lines of code!

Step 3: Mapper Utility

public class ProductMapper {

    public static ProductDTO toDTO(Product product) {
        return new ProductDTO(
                product.getId(),
                product.getName(),
                product.getDescription(),
                product.getPrice()
        );
    }

    public static Product toEntity(ProductDTO dto) {
        Product product = new Product();
        product.setName(dto.name());
        product.setDescription(dto.description());
        product.setPrice(dto.price());
        return product;
    }
}

Step 4: Repository Layer

public interface ProductRepository extends JpaRepository<Product, Long> {
}

Step 5: Service Layer

@Service
public class ProductService {

    private final ProductRepository repository;

    public ProductService(ProductRepository repository) {
        this.repository = repository;
    }

    public List<ProductDTO> getAllProducts() {
        return repository.findAll()
                .stream()
                .map(ProductMapper::toDTO)
                .toList();
    }

    public ProductDTO createProduct(ProductDTO dto) {
        Product product = ProductMapper.toEntity(dto);
        Product saved = repository.save(product);
        return ProductMapper.toDTO(saved);
    }
}

Step 6: REST Controller

@RestController
@RequestMapping("/api/products")
public class ProductController {
    private final ProductService service;

    public ProductController(ProductService service) {
        this.service = service;
    }

    @GetMapping
    public List<ProductDTO> getAllProducts() {
        return service.getAllProducts();
    }

    @PostMapping
    public ProductDTO createProduct(@RequestBody ProductDTO dto) {
        return service.createProduct(dto);
    }
}

💡 Using Records for Custom API Responses

public record ApiResponse<T>(String message, T data, LocalDateTime timestamp) {}

Example Usage:

@GetMapping
public ApiResponse<List<ProductDTO>> getAll() {
    return new ApiResponse<>("Products fetched", service.getAllProducts(), LocalDateTime.now());
}

✅ Looks great, minimal code, and makes the API more structured.

🚀 Using Records with Spring Data Projections

You can return a record from a custom JPQL query:

public record ProductView(Long id, String name) {}

@Query("SELECT new com.example.demo.ProductView(p.id, p.name) FROM Product p")
List<ProductView> findAllProductNames();

⚠️ Things You CANNOT Do with Records

Best Practices

1. ✅ Use records only when immutability makes sense (e.g., DTOs, value models).
2. ❌ Don’t use records for JPA entities (JPA requires mutable fields).
3. ✅ Combine records with @RequestBody or @ResponseBody for cleaner REST APIs.
4. ✅ Use records for in-memory and read-only operations.
5. ✅ Use records in unit tests for mock payloads and expected results.

Unit Test Example

@Test
void testProductDTO() {
    ProductDTO dto = new ProductDTO(1L, "Book", "Java Book", 399.99);
    assertEquals("Book", dto.name());
}

Frameworks and Libraries That Work Well with Records

📚 Summary

• Java records are lightweight, immutable data carriers.
• In Spring Boot, they’re perfect for DTOs, responses, and projections.
• They reduce boilerplate, improve readability, and encourage immutability.
• But avoid using them as entities or for mutable state.

🎯 Final Thoughts

Java Records bring the modern, minimalist syntax we’ve long wanted in Java. When combined with Spring Boot, they offer a clean, professional structure — especially for REST APIs, microservices, and cloud-native applications.

✅ Cleaner code
✅ Fewer bugs
✅ Easier maintenance

Still using POJOs for DTOs? It’s time to upgrade to Java Records and experience the simplicity.