SLF4J in distributable library, how to obtain Logger

Question

I want to distribute a lib relying on the SLF4J logger interface. What is the best practice way to obtain the logger which integrate nicely into any other project? Sorry for the unstructured question style, I'm still trying to figure out how all this stuff is glued together.

In other projects I always use this piece of code, because I want to obtain a custom logger:

private final static Logger LOGGER = LoggerFactory.getILoggerFactory().getLogger(NAME_OF_APP);

If I create the class org.slf4j.impl.StaticLoggerBinder and have it some other lib, does the therein defined factory get used even if I just call LoggerFactory.getLogger(NAME_OF_APP) or is some default slf4j factory used?

I want the user to be able to use his own factory and logger, so which way is to perfere, and most of all why?

Answer 1

I'm not sure I fully understand what you are trying to do.

SLF4J is composed of two parts. First the API which you use in your lib to code your logging calls. And secondly the implementation which you use during your development to do logging, but DO NOT set as a dependency of the lib.

Because SLF4J looks for the implementations on the class path the developers using our lib can simple include any implementation they want. Sometimes is some quite strange ways :-) They can use a range of prebuilt implementations or code their own. It's up to them.

I don't think you need to do anything more than just use SLF4J's API as is.

Answer 2

From http://slf4j.org/manual.html

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

public class HelloWorld {
  public static void main(String[] args) {
    Logger logger = LoggerFactory.getLogger(HelloWorld.class);
    logger.info("Hello World");
  }
}

So, always use LoggerFactory.getLogger(...). The argument allow the logger backend to determine the behavior of the logger returned to you.