How do I fix SLF4J class path contains multiple SLF4J bindings?

If you are looking for quick solution for this issue, you need to find out how log4j is present on your path. run mvn dependency:tree and figure out the maven dependency and exclude log4j with snippet below to that dependency in your pom. xml . This should resolve SLF4J: Class Path Contains Multiple SLF4J Bindings.

What are SLF4J bindings?

Bindings are basically implementations of a particular SLF4J class meant to be extended to plug in a specific logging framework. By design, SLF4J will only bind with one logging framework at a time. Consequently, if more than one binding is present on the classpath, it will emit a warning.

How does SLF4J binding work?

The “binding” happened when the SLF4J developers created libraries to handle the most popular Java logging frameworks. When the docs say that the “binding is hardwired at compile time,” it means the SLF4J developers have created a targeted library for a particular Java logging framework.

How do I exclude a Logback Classic?

Remove the jar from while packeging by adding this “excludeGroupIds log4j-slf4j-impl /excludeGroupIds” Find out the which library is depends on “logback-classic” by using command “mvn dependecy:tree” Wherever you find it exclude it from the dependency.

What is SLF4J?

SLF4J stands for Simple Logging Facade for Java. It provides a simple abstraction of all the logging frameworks. It enables a user to work with any of the logging frameworks such as Log4j, Logback, JUL (java.

What is SLF4J vs log4j?

SLF4J(Simple Logging Façade for java) is an API designed to give generic access to many logging frameworks, log4j being one of them. It is basically an abstraction layer. It is not a logging implementation. In the case of Log4j, it is a logging component, and it does the logging instructed to do.

What is the difference between SLF4J and log4j?

Can we use log4j and SLF4J together?

Once you have places both jar files in your application classpath, SLF4j will automatically detect it and start using log4j for processing the log statements based on configuration you provided in log4j configuration file. So essentially, SLF4J does not replace log4j, they work together.

How do I add exclusions in POM XML?

Exclude the transitive dependency

Open the dependency POM and find the transitive dependency you want to exclude. Copy groupId and artifactId .
In your project POM, underneath your active dependency, enter exclusions and using code completion paste the copied info of the dependency you want to exclude. tip.

What is Ch QOS Logback?

Logback Project Logback is intended as a successor to the popular log4j project, picking up where log4j leaves off. Moreover, logback-classic natively implements the SLF4J API so that you can readily switch back and forth between logback and other logging frameworks such as log4j or java.

What is SLF4J used for?

This is the main purpose of SLF4J (Simple Logging Facade for Java) – a logging abstraction which helps to decouple your application from the underlying logger by allowing it to be plugged in – at runtime. Of course, the flexibility that such an abstraction provides is the main reason to use SLF4J.

Can we use SLF4J instead of log4j?

All these SLF4J implementations are all available: An application coded against the Log4j2 API can select the log4j-to-slf4j dependency instead of log4j-core and choose any of these SLF4J implementations you mentioned.

Why are there multiple SLF4J bindings in the classpath?

SLF4J: Class path contains multiple SLF4J bindings. This is due to multiple jar files having definition of /org/slf4j/impl/StaticLoggerBinder.class . The warnings will no longer appear. The script is designed to remove reference to one of the jar file in the classpath.

Why does SLF4J emit warning when there is more than one logging framework?

By design, SLF4J will only bind with one logging framework at a time. Consequently, if more than one binding is present on the classpath, it will emit a warning. It is worth noting that embedded components such as libraries or frameworks should never declare a dependency on any SLF4J binding.

Are there any SLF4J bindings in Logback classic?

This warning is telling us that SLF4J has found two bindings. One is in slf4j-log4j12-1.7.21.jar and the other in logback-classic-1.1.7.jar. Now, let’s understand why we see this warning.

Can a SLF4J jar be loaded in protected class loader?

This APAR allows the OSGi Applications feature pack to declare that the SLF4J jars bundled with the feature pack are now loaded in the protected class loader. This means applications can load there own version of the SLF4J jar without interference from this bundled version.