Step-by-Step Guide: Replacing JUL with Log4j2 and Integrating SLF4J

In a previous article, I covered how to integrate SLF4J with java.util.logging (JUL). While JUL works fine for many applications, Log4j2 offers more powerful features such as asynchronous logging, better performance, and flexible configuration options.

This article builds on that foundation and shows you how to replace JUL with Log4j2, while still leveraging SLF4J for a clean, consistent logging API. If you’re looking to move away from JUL or want to explore Log4j2 for its advanced capabilities, this guide is for you.

To help you get started, I have created a feature branch named feature/migrate-to-log4j2 in the GitHub repository jul-with-slf4j-logging, which holds all the adaptations for the migration to Log4j2. You can follow this guide and use the code available in the branch for reference.

Table of Contents

1. Introduction to Log4j2 and SLF4J
2. Prerequisites
3. Adding Dependencies
4. Configuration Steps
5. Testing the Setup
6. Best Practices
7. Troubleshooting Common Issues
8. Conclusion

Introduction to Log4j2 and SLF4J