Project Lombok Annotations with Examples

Java, while being a powerful and versatile language, often comes with a side of verbosity. Boilerplate code can often overshadow the business logic, making the code harder to read and maintain. Project Lombok is an initiative that aims to counter this by introducing a set of annotations to help minimize this boilerplate. In this post, we will explore some of the popular Lombok annotations, understand their purpose, see examples, and enumerate the benefits.

1. @Getter and @Setter 

Instead of manually writing getters and setters for each field in your class, you can use Lombok's @Getter and @Setter annotations. 

Example without Lombok: 

public class User {
    private String name;
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
}

With Lombok:

import lombok.Getter;
import lombok.Setter;

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

Benefits: 

• Reduces lines of code. 
• Auto-generated code ensures fewer human errors. 
• Makes the class more readable.

2. @NoArgsConstructor 

Generates a no-arguments constructor. 

Example with Lombok:

import lombok.NoArgsConstructor;

@NoArgsConstructor
public class User {
    private String name;
}

This will generate a default constructor like:

public User {
}

3. @AllArgsConstructor 

Generates a constructor with arguments for all fields in your class. 

Example with Lombok:

import lombok.AllArgsConstructor;

@AllArgsConstructor
public class User {
    private String name;
}

This will generate a constructor like: 

public User(String name) {
    this.name = name;
}

 4. @RequiredArgsConstructor 

Generates a constructor with arguments for all fields that are marked as final, or are marked with @NonNull, and not initialized where they are declared. 

Example with Lombok:

import lombok.RequiredArgsConstructor;

@RequiredArgsConstructor
public class User {
    private final String name;
    private int age;
}

This will generate a constructor like: 

public User(String name) {
    this.name = name;
}

Benefits of Using Constructor Annotations: 

• Eliminates the need to manually create constructors. 
• Ensures consistency as fields are added or removed. 
• Enhances code readability by reducing boilerplate.

5. @Data 

@Data annotation is a shortcut for @ToString, @EqualsAndHashCode, @Getter on all fields, and @Setter on all non-final fields, and @RequiredArgsConstructor! 

With Lombok:

import lombok.Data;

@Data
public class Product {
    private String id;
    private String name;
}

Benefits: 

• Complete boilerplate code reduction for standard class methods.
• A one-stop annotation for common requirements.

6. @Slf4j 

This annotation creates and injects a logger into your class. 

With Lombok:

import lombok.extern.slf4j.Slf4j;

@Slf4j
public class LoggerExample {
    public void logSomething() {
        log.info("This is an info message!");
    }
}

Benefits: 

• No need to manually define the logger.
• Simplifies logging code.

7. @Builder 

Implement the Builder pattern without coding the boilerplate. 

With Lombok:

import lombok.Builder;

@Builder
public class Vehicle {
    private String type;
    private String color;
    private int wheels;
}

Usage:

Vehicle car = Vehicle.builder()
                .type("Car")
                .color("Blue")
                .wheels(4)
                .build();

Benefits:

• Fluent API style initialization.
• Reduces complexity in classes with many parameters.

Conclusion

Project Lombok has an array of annotations, each with the purpose to simplify Java code. By incorporating these annotations, developers can maintain the core focus on the logic rather than the repetitive boilerplate. It not only beautifies the code but also enhances its readability and maintainability. Happy coding with fewer lines!