Spring Boot Using Lombok – Detailed Explanation

Project Lombok is a Java library that helps reduce boilerplate code in Spring Boot applications by generating commonly used methods at compile time.

What is Lombok?

Lombok automatically generates:

• Getters and Setters
• Constructors
• toString()
• equals() and hashCode()
• Builder pattern
• Logger variables

Lombok works at compile time, so there is no runtime performance impact.

Why Use Lombok in Spring Boot?

• Reduces boilerplate code
• Improves code readability
• Faster development
• Cleaner Git commits
• Lower chance of human errors

Adding Lombok to Spring Boot Project

Maven Dependency

    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>
    

The optional=true flag ensures Lombok is not packaged in the final JAR.

IDE Configuration

• IntelliJ IDEA: Install Lombok plugin and enable Annotation Processing
• Eclipse: Install Lombok and enable annotation processing

Common Lombok Annotations

1. @Getter and @Setter

Generates getter and setter methods automatically.

    @Getter
    @Setter
    public class User {
        private Long id;
        private String name;
    }
    

2. @NoArgsConstructor

Generates a no-argument constructor. Required for JPA and Jackson.

    @NoArgsConstructor
    public class User {
    }
    

3. @AllArgsConstructor

Generates a constructor with all fields.

    @AllArgsConstructor
    public class User {
        private Long id;
        private String name;
    }
    

4. @RequiredArgsConstructor

Generates a constructor for final and @NonNull fields.

    @RequiredArgsConstructor
    @Service
    public class OrderService {
        private final OrderRepository orderRepository;
    }
    

This is the recommended approach for Spring dependency injection.

5. @ToString

Generates the toString() method.

    @ToString
    public class User {
        private Long id;
        private String name;
    }
    

Avoid using it on JPA entities with relationships.

6. @EqualsAndHashCode

Generates equals() and hashCode() methods.

    @EqualsAndHashCode(onlyExplicitlyIncluded = true)
    public class User {
        @EqualsAndHashCode.Include
        private Long id;
    }
    

7. @Data

Shortcut annotation that combines multiple Lombok features.

    @Data
    public class UserDTO {
        private Long id;
        private String name;
    }
    

Recommended for DTOs, but not for JPA entities.

8. @Builder

Implements the Builder pattern for object creation.

    @Builder
    public class UserDTO {
        private Long id;
        private String name;
    }
    

Usage:

    UserDTO user = UserDTO.builder()
            .id(1L)
            .name("Sandeep")
            .build();
    

9. @Slf4j

Automatically creates a logger instance.

    @Slf4j
    @Service
    public class UserService {
    
        public void saveUser() {
            log.info("Saving user");
        }
    }
    

10. @NonNull

Adds null-check validation automatically.

    public User(@NonNull String name) {
    }
    

Lombok Usage by Application Layer

Entity Layer (JPA)

    @Entity
    @Getter
    @Setter
    @NoArgsConstructor
    @AllArgsConstructor
    public class User {
        @Id
        private Long id;
        private String name;
    }
    

Avoid using @Data and @ToString on entities.

DTO Layer

    @Data
    @Builder
    @NoArgsConstructor
    @AllArgsConstructor
    public class UserDTO {
        private Long id;
        private String name;
    }
    

Service Layer

    @Service
    @RequiredArgsConstructor
    @Slf4j
    public class UserService {
        private final UserRepository userRepository;
    }
    

Lombok Interview Questions (Quick)

• Does Lombok affect performance? No, it works at compile time.
• Is Lombok production safe? Yes.
• Why avoid @Data in entities? Can cause lazy loading and recursion issues.

Pros and Cons of Lombok

Pros

• Less boilerplate
• Cleaner code
• Faster development

Cons

• IDE dependency
• Overuse can hide logic

Summary

Lombok simplifies Spring Boot development by reducing repetitive code. Use it wisely by selecting appropriate annotations based on application layers.