Is it worth to use slf4j with log4j2

java

logging

best-practices

performance

byNikita Barsukov·Feb 25, 2025

Quickly, the answer is yes. Using SLF4J with Log4j2 is a solid choice. SLF4J gives you "one ring to rule them all" - a single facade offering framework swapping and cleaner parameterized logging. Meanwhile, Log4j2 is all about performance and a thorough wealth of features.

Here's a little taste with SLF4J and Log4j2:

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

public class HelloWorld {
    private static final Logger logger = LoggerFactory.getLogger(HelloWorld.class);

    public void sayHello() {
        // Look, Ma! No string concatenation!
        logger.info("Hello, {}!", "World"); 
    }
}

Combine SLF4J and Log4j2 and you get the perfect blend: flexibility and efficiency.

Opting between SLF4J and Log4j2 API

Consider these key points when you're juggling between SLF4J and Log4j2 API:

Access to features: Using Log4j2 API directly opens doors to its complete feature set, a richness you might not get via SLF4J.
Managing dependencies: A cleaner dependency hierarchy is a happy one. Log4j2 API demands fewer dependencies. (Who doesn't love less bloat?)
Scalability concerns: Take note that Log4j2 is commited to garbage-free logging, a boon for performance-critical applications.

The edge of using Log4j2 directly

There's more to it - check out these exclusive benefits of Log4j2 API:

Advanced functionalities: Discover Log4j2 API's capability to create custom Message objects and support for modern Java features, like lambda expressions. (Slice and dice to your heart's content!)
Simplicity: Bypass the "facade for a facade" and enjoy a more straightforward, less tangled implementation. Your future self will thank you.
Keeping doors open: Stick with Log4j2 API and reserve the right to leverage the growing ecosystem of log appenders, filters and layouts.
Integration: Fear not - There's a log4j-to-slf4j bridge! Use SLF4J with Log4j2, smoothly weaving the best of both worlds.

When SLF4J is a safer bet

Although Log4j2 offers tempting indulgences, SLF4J stands tall as ever:

Building Libraries: SLF4J secures broad compatibility - crucial when your role is a library developer.
Stability over novelty: Older isn't always worse. SLF4J's significance lies in its stability, and sometimes that wins over Log4j2's feature set.
Future-proofing: Choose with the future in mind. Consider the pace your project moves at and whether SLF4J's safety is more comforting than Log4j2's edge.

Considerations for your project's future

It's a decision that reverberates. Weigh in these factors on your project's future:

Project maintenance: Going with a unified logging framework like Log4j2 eliminates unnecessary complexity.
Code Modernization: Ask yourself - How eager are you to embrace Java's modern features?
Performance Tuning: Got a performance-hungry beast? The garbage-free nature of Log4j2 might just be the fuel it needs.

Balancing the pros and cons

The endeavor to balance staple reliability and exciting possibilities can be a high-wire act:

Custom Message Flexibility: Log4j2 API lets you tailor log messages like a finely stitched suit.
Selective Integration: The log4j-to-slf4j bridge allows selective use - just like taking the right spices for your favorite dish.
Legacy Support vs Future Across: Sometimes, balancing nostalgia with novelty is key. SLF4J's stability vs Log4j2's push to the bleeding edge - it's your call.

Diverse project, diverse needs

One size doesn't fit all. Eclectic projects demand diverse considerations:

Adopting or Adapting: What's your style - eager early adoption, or careful adaptationwith a proven logging API?
Logging Complexity: Heavily multifaceted applications could leverage the advanced features offered by Log4j2.
Future Foresight: Here's a riddle: What impacts your project tomorrow but is chosen today? Your logging tool!