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Welcome to the kotlin-logging wiki!

kotlin-logging is a lightweight logging framework for Kotlin. A convenient and performant logging library wrapping slf4j with Kotlin extensions kotlin-logging provides both:

• Idiomatic way to obtain a logger without the need to specify class name
• Enhanced logging api that integrates fluently with Kotlin

Install

Add the below dependency to start using kotlin-logging.

Maven

<dependency>
  <groupId>io.github.microutils</groupId>
  <artifactId>kotlin-logging</artifactId>
  <version>1.4</version>
</dependency>

Gradle

compile 'io.github.microutils:kotlin-logging:1.4'

Important note: kotlin-logging depends on slf4j-api, but it is also required to depend on a logging implementation in runtime. More details here.

Getting started

class FooWithLogging {
    companion object: KLogging()
    val message = "world"
    fun bar() {
        logger.info{"hello $message"}
    }
}

Usage

The recommended usage is to have the Companion object extends KLogging() and using the logger member in the class like that:

companion object: KLogging()

Then using the logger:

logger.info("hello message")

For sequences that are expected to be frequently used prefer lazy evaluated messages:

logger.debug{"lazy evaluated $hello message"}

(String is inside a method and gets evaluated only if debug log level is enabled at runtime)

In cases the Companion object already extending other class it is recommend to implement the KLoggable interface:

companion object: Any(), KLoggable {
  override val logger = logger()
  ...
}

Other (less recommended) alternatives are:

companion object: Any(), KLoggable by NamedKLogging("com.MyClass")

Or implementing it as a non static member:

class ClassHasLogging: KLoggable {
    override val logger = logger()
    fun test() {
        logger.info{"hello message"}
    }
}