I am using Spring boot. Spring boot by default comes with logback. I wanted to use log4j (for whatever reasons..)

In order to do that I had to exclude logback and add new log4j dependencies:

Logback is “hidden” inside this package:

compile("org.springframework.boot:spring-boot-starter:$project.ext.springBootVersion")
 {
 exclude module: 'org.springframework.boot:spring-boot-starter-logging'
}

compile("org.springframework.boot:spring-boot-starter-log4j:$project.ext.springBatchVersion")

Now when you try to run app you get this Exception:

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/C:/dev/caches/modules-2/files-2.1/org.slf4j/slf4j-log4j12/1.7.10/b3eeae7d1765f988a1f45ea81517191315c69c9e/slf4j-log4j12-1.7.10.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/C:/dev/caches/modules-2/files-2.1/ch.qos.logback/logback-classic/1.1.2/b316e9737eea25e9ddd6d88eaeee76878045c6b2/logback-classic-1.1.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]

Now we have to look at Gradle’s dependencies tree to see where logback is hidden in order to eliminate it.

Simple command to see gradle’s dependencies tree:

gradle -q dependencies web:dependencies --configuration compile

* web stands for your module name.

Snap view of the output:

Project :web - web
 ------------------------------------------------------------

 compile - Compile classpath for source set 'main'.
 +--- org.springframework.boot:spring-boot-starter-actuator:1.2.2.RELEASE
 | +--- org.springframework.boot:spring-boot-starter:1.2.2.RELEASE
 | | +--- org.springframework.boot:spring-boot:1.2.2.RELEASE
 | | | +--- org.springframework:spring-core:4.1.5.RELEASE
 | | | | \--- commons-logging:commons-logging:1.2
 | | | \--- org.springframework:spring-context:4.1.5.RELEASE
 | | | +--- org.springframework:spring-aop:4.1.5.RELEASE
 | | | | +--- aopalliance:aopalliance:1.0
 | | | | +--- org.springframework:spring-beans:4.1.5.RELEASE
 | | | | | \--- org.springframework:spring-core:4.1.5.RELEASE (*)
 | | | | \--- org.springframework:spring-core:4.1.5.RELEASE (*)
 | | | +--- org.springframework:spring-beans:4.1.5.RELEASE (*)
 | | | +--- org.springframework:spring-core:4.1.5.RELEASE (*)
 | | | \--- org.springframework:spring-expression:4.1.5.RELEASE
 | | | \--- org.springframework:spring-core:4.1.5.RELEASE (*)
 | | +--- org.springframework.boot:spring-boot-autoconfigure:1.2.2.RELEASE
 | | | +--- org.springframework.boot:spring-boot:1.2.2.RELEASE (*)
 | | | \--- org.yaml:snakeyaml:1.14
 | | +--- org.springframework.boot:spring-boot-starter-logging:1.2.2.RELEASE
 | | | +--- org.slf4j:jcl-over-slf4j:1.7.10
 | | | | \--- org.slf4j:slf4j-api:1.7.10
 | | | +--- org.slf4j:jul-to-slf4j:1.7.10
 | | | | \--- org.slf4j:slf4j-api:1.7.10
 | | | +--- org.slf4j:log4j-over-slf4j:1.7.10
 | | | | \--- org.slf4j:slf4j-api:1.7.10
 | | | \--- mycompany:logback-classic:1.1.2
 | | | +--- mycompany:logback-core:1.1.2
 | | | \--- org.slf4j:slf4j-api:1.7.6 -> 1.7.10
 | | +--- org.springframework:spring-core:4.1.5.RELEASE (*)
 | | \--- org.yaml:snakeyaml:1.14
 | +--- org.springframework.boot:spring-boot-actuator:1.2.2.RELEASE

We can find one of the instances of logback popping up from one of our dependencies:

mycompany:logback-core:1.1.2

(I found logback show’s  in other dependencies).

Now we have two options:

1. Exclude each logback’s route with-in the indecencies tree
2. Use configuration-wide exclusion (the easier way)

So go to your build.gradle and add this:

configurations {
 compile.exclude group:'ch.qos.logback'
}

Thats it. Your nightmare is over. If you check the dependencies tree again you wont see any existence of logback anymore.