Java Records vs. Lombok

In the evolving landscape of Java, developers often seek efficient ways to reduce boilerplate code, particularly for data-holding classes. Two popular approaches for achieving this are Java Records, introduced in Java 14 (standardized in Java 16), and Project Lombok, an established third-party library. In this blog post, we'll explore the differences and similarities between Java Records and Lombok, using examples to highlight their features and use cases.

What are Java Records? 

Java records are a type of class designed for holding immutable data. They automatically provide implementations for methods like equals()hashCode(), and toString(), significantly reducing boilerplate code. This makes them ideal for creating Data Transfer Objects (DTOs), entities, and other model classes in a Spring Boot application. 

Example of Java Record 

Let’s consider a simple example of a Java Record to represent a Person.

public record Person(String name, int age) {}

In this example, Person is a record with two fields: name and age. Java automatically provides the following for this record: 

A public constructor: Person(String name, int age) 

Public getter methods: name() and age() 

Implementations of equals()hashCode(), and toString()

Using Getter Methods

One of the key features of records is that they provide implicit getter methods for accessing the fields. These methods are named after the fields themselves.

Here's how you can create an instance of Person and use its getter methods:

public class Main {
    public static void main(String[] args) {
        Person person = new Person("Alice", 30);

        // Using getter methods
        String name = person.name();
        int age = person.age();

        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
    }
}

Output:

Name: Alice
Age: 30

What is Lombok? 

Lombok is a Java library that plugs into your editor and build tools, simplifying your code by generating boilerplate code like getters, setters, constructors, and more through annotations. 

Example of Lombok Data Class

import lombok.Data;

@Data
public class Person {
    private final String name;
    private final int age;
}

The @Data annotation generates all the getters, a useful toString method, and equals and hashCode implementations.

Usage:

Person person = new Person("Alice", 30);
System.out.println(person.getName());  // Alice
System.out.println(person.getAge());   // 30

Difference Between Java Records and Lombok

1. Boilerplate Reduction

Java Records

The Java Records are designed to minimize boilerplate to its bare minimum for data-holding objects.
public record User(Long id, String name, String email) {}

This single line automatically generates a constructor, getters, and equals, hashCode, and toString methods.

Lombok

The Lombok provides annotations to eliminate boilerplate code but requires explicit annotations for each feature.
import lombok.Data;

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

The @Data annotation generates getters, setters, required constructors, and the same methods as records, but you need to include the Lombok library and annotations.

2. Immutability

Java Records

Java Records are immutable by default. All fields are final, and there are no setters.
public record User(Long id, String name) {}
// User's fields are final and cannot be changed after creation.

Records are immutable by default.

Lombok

Lombok offers both mutable and immutable options. The immutability depends on how you annotate your class.
import lombok.Value;

@Value
public class User {
    Long id;
    String name;
}
// Similar to records, @Value makes fields final and generates only getters.

Lombok can create immutable classes using @Value, but it's not the default behavior.

3. Constructors

Java Records

Java Records automatically provides a public constructor with all fields as parameters.
public record User(Long id, String name) {}
// Implicit constructor: User(Long id, String name)

Records provide an implicit public constructor matching all its fields.

Lombok

With @AllArgsConstructor, @NoArgsConstructor, or @RequiredArgsConstructor, you can generate various types of constructors.
import lombok.AllArgsConstructor;

@AllArgsConstructor
public class User {
    private Long id;
    private String name;
}
// Generates a constructor with all fields: User(Long id, String name)

Lombok requires an @AllArgsConstructor annotation to generate a similar constructor.

4. Readability and Transparency

Java Records

Java Records are highly readable and transparent, with a clear indication that the class is a simple data holder.
public record User(Long id, String name) {}

Records clearly define their purpose as data carriers.

Lombok

While Lombok reduces code, the presence of annotations and the absence of explicit methods can affect readability for those unfamiliar with Lombok.
import lombok.Data;

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

Lombok enhances readability by reducing boilerplate but can be less transparent to those unfamiliar with its annotations.

5. Compatibility and Use Cases

Java Records

Java Records are best suited for simple data transport objects, especially where immutability is desired.
public record UserDTO(Long id, String name) {}

Lombok

Lombok is more flexible, suitable for both mutable and immutable classes, and offers a wider range of features beyond what records provide.
import lombok.Data;
import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
@Data
public class UserEntity {
    @Id
    private Long id;
    private String name;
}

6. Tooling and Integration

Java Records

Being a part of the Java language, records are universally supported across tools and IDEs without additional plugins.

Lombok

Requires integration into your build tool and IDE. While widely supported, this can sometimes lead to issues with setup and tool compatibility.

Conclusion

Java Records and Lombok both serve the purpose of reducing boilerplate code in Java, but they approach this goal differently. Records offer a language-level solution with a focus on immutability and data transparency, ideal for simple, immutable data objects. Lombok, on the other hand, provides a more flexible annotation-driven approach, suitable for a wider variety of use cases.

The choice between Java Records and Lombok will depend on your specific needs, preferences, and project complexity. As Java continues to evolve, it will be interesting to see how these two approaches coexist and complement each other in the Java ecosystem.

Comments