[JAVA] What is SLF4J?


Stumble on an error What is SLF4J in the first place? I looked it up from that place.

[Error statement]

java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory

What is SLF4J?

SLF4J is a simple façade for logging systems that allows end users to plug in the desired logging system during deployment.

What is a façade?

The Facade class is a class that organizes a group of classes that are complicated to use and provides them to the outside as an easy-to-use interface. In the design pattern, the pattern that uses this Facade class is called the Facade pattern. (By the way, Facade is a word that means "window")

[Literal translation] Simple Logging Facade for Java (SLF4J) acts as a simple facade or abstraction for various logging frameworks (java.util.logging, logback, log4j, etc.) Allows end users to plug in the desired logging framework at deployment time.

Enabling the library on SLF4J is a single mandatory dependency, Note that this means adding slf4j-api.jar. If no binding is found in the classpath, SLF4J will default to a non-working implementation.

If you want to migrate Java source files to SLF4J Consider a migrator tool that can migrate your project to use the SLF4J API in minutes.

Binary support for SLF4J for legacy APIs, like commons logging, log4j, java.util.logging, if the externally maintained component you depend on uses a logging API other than SLF4J. Please take a look.

※important point If no binding is found in the classpath, SLF4J will default to a non-working implementation.


Referenced article (Thank you always.)

Organize the relationship between SLF4J, Logback, and Log4J along with their behavior.

Simple Logging Facade for Java (SLF4J)

Frequently Asked Questions about SLF4J

Facade pattern in java

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