<< Back to Project Lombok Tutorial

In this post, I will show you how to reduce boilerplate code while logging in Java applications using Project Lombok @Slf4j annotation with an example.

Project Lombok Maven

Create a simple maven project using - How to Create a Simple Maven Project in Eclipse article.
Add the below dependency in your maven project pom.xml file:

<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.18.4</version>
    <scope>provided</scope>
</dependency>

Adding the Lombok Plugin in IDE (Eclipse)

Follow below steps to install Lombok in eclipse for Windows:

Downloaded jar from https://projectlombok.org/download or use the jar which is downloaded from your maven build.
Execute command in terminal: java -jar lombok.jar
This command will open window as shown in the picture below, install and quit the installer and restart eclipse.

Without Project Lombok

Let's write a source code without using Project Lombok:

package net.javaguides.lombok.logging;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import net.javaguides.lombok.User;

public class UserService {
    public static final Logger LOGGER = LoggerFactory.getLogger(UserService.class);

    public void saveUser() {
        LOGGER.debug("inside saveUser() method");
    }

    public void updateUser() {
        LOGGER.debug("inside updateUser() method");
    }

    public User findUser(long id) {
        LOGGER.debug("inside findUser() method");
        LOGGER.info(new Long(id).toString());
        return null;
    }

    public void deleteUser(long id) {
        LOGGER.debug("inside deleteUser() method");
        LOGGER.info(new Long(id).toString());
    }
}

With Project Lombok

Let's re-write above code using Project Lombok @Slf4j annotation:

package net.javaguides.lombok.logging;

import lombok.extern.slf4j.Slf4j;
import net.javaguides.lombok.User;

@Slf4j
public class UserServiceLombok {

    public void saveUser() {
        log.debug("inside saveUser() method");
    }

    public void updateUser() {
        log.debug("inside updateUser() method");
    }

    public User findUser(long id) {
        log.debug("inside findUser() method");
        log.info(new Long(id).toString());
        return null;
    }

    public void deleteUser(long id) {
        log.debug("inside deleteUser() method");
        log.info(new Long(id).toString());
    }

    public static void main(String[] args) {
        UserServiceLombok userService = new UserServiceLombok();
        userService.saveUser();
        userService.updateUser();
        userService.deleteUser(100 L);
        userService.findUser(100 L);
    }
}