CODEWITHSUNDEEP
javaeclipsemavenpom.xmlslf4j
pzsette
pzsette

Reputation: 346

SLF4J: Class path contains multiple SLF4J bindings warning

I've seen in other questions that usually the solution to this warning is to exclude slf4j from the dependency that causes this conflict, but I can't spot the problem in my project.

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/Applications/Eclipse.app/Contents/Eclipse/plugins/org.eclipse.m2e.maven.runtime.slf4j.simple_1.16.0.20200610-1735/jars/slf4j-simple-1.7.5.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [file:/Applications/Eclipse.app/Contents/Eclipse/configuration/org.eclipse.osgi/5/0/.cp/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.slf4j.impl.SimpleLoggerFactory]
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/Applications/Eclipse.app/Contents/Eclipse/plugins/org.eclipse.m2e.maven.runtime.slf4j.simple_1.16.0.20200610-1735/jars/slf4j-simple-1.7.5.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [file:/Applications/Eclipse.app/Contents/Eclipse/configuration/org.eclipse.osgi/5/0/.cp/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.slf4j.impl.SimpleLoggerFactory]

I run mvn dependency:tree command and this is the output:

[INFO] --- maven-dependency-plugin:2.8:tree (default-cli) @ subscriptionsmanager ---
[INFO] it.pietro:subscriptionsmanager:jar:0.0.1-SNAPSHOT
[INFO] +- junit:junit:jar:4.13.1:test
[INFO] |  \- org.hamcrest:hamcrest-core:jar:1.3:test
[INFO] +- org.mockito:mockito-core:jar:3.5.13:test
[INFO] |  +- net.bytebuddy:byte-buddy:jar:1.10.15:test
[INFO] |  +- net.bytebuddy:byte-buddy-agent:jar:1.10.15:test
[INFO] |  \- org.objenesis:objenesis:jar:3.1:test
[INFO] +- org.mongodb:mongo-java-driver:jar:3.12.7:compile
[INFO] +- ch.qos.logback:logback-classic:jar:1.2.3:compile
[INFO] |  +- ch.qos.logback:logback-core:jar:1.2.3:compile
[INFO] |  \- org.slf4j:slf4j-api:jar:1.7.25:compile
[INFO] +- de.bwaldvogel:mongo-java-server:jar:1.11.1:compile
[INFO] |  +- de.bwaldvogel:mongo-java-server-core:jar:1.11.1:compile
[INFO] |  |  +- io.netty:netty-transport:jar:4.1.31.Final:compile
[INFO] |  |  |  +- io.netty:netty-buffer:jar:4.1.31.Final:compile
[INFO] |  |  |  |  \- io.netty:netty-common:jar:4.1.31.Final:compile
[INFO] |  |  |  \- io.netty:netty-resolver:jar:4.1.31.Final:compile
[INFO] |  |  \- io.netty:netty-codec:jar:4.1.31.Final:compile
[INFO] |  \- de.bwaldvogel:mongo-java-server-memory-backend:jar:1.11.1:compile
[INFO] +- org.assertj:assertj-core:jar:3.15.0:test
[INFO] +- org.testcontainers:mongodb:jar:1.15.1:compile
[INFO] |  \- org.testcontainers:testcontainers:jar:1.15.1:compile
[INFO] |     +- org.apache.commons:commons-compress:jar:1.20:compile
[INFO] |     +- org.rnorth.duct-tape:duct-tape:jar:1.0.8:compile
[INFO] |     +- org.rnorth.visible-assertions:visible-assertions:jar:2.1.2:compile
[INFO] |     |  \- net.java.dev.jna:jna:jar:5.2.0:compile
[INFO] |     +- com.github.docker-java:docker-java-api:jar:3.2.7:compile
[INFO] |     |  \- com.fasterxml.jackson.core:jackson-annotations:jar:2.10.3:compile
[INFO] |     \- com.github.docker-java:docker-java-transport-zerodep:jar:3.2.7:compile
[INFO] |        \- com.github.docker-java:docker-java-transport:jar:3.2.7:compile
[INFO] +- org.assertj:assertj-swing-junit:jar:3.17.1:test
[INFO] |  +- org.assertj:assertj-swing:jar:3.17.1:test
[INFO] |  |  \- org.easytesting:fest-util:jar:1.2.5:test
[INFO] |  \- org.easytesting:fest-reflect:jar:1.4.1:test
[INFO] \- info.picocli:picocli:jar:4.5.2:compile

Upvotes: 5

Views: 12387

Answers (2)

tapsshore
tapsshore

Reputation: 292

You can solve the issue by adding the following exclusion in the dependencies (of pom.xml) that caused conflict.

 <exclusions>
    <exclusion>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
    </exclusion>
 </exclusions>

Upvotes: 0

howlger
howlger

Reputation: 34305

The SLF4J bindings warning comes from the Eclipse IDE itself and is not related to your application you write in the Eclipse IDE. So it's just noise that can be ignored (see e.g. here and here).

I guess you have the Eclipse IDE for Enterprise Java Developers with maybe some additional plugins installed. That's more than 900 JARs. SLF4J is used by the Maven support for Eclipse (in the SLF4J bindings warning as m2e) and also by at least one other plugin in an incompatible way causing this warnings. Eclipse is based on OSGi where there is not a flat classpath and where plugins/bundles can be installed, started, stopped and uninstalled at runtime. SLF4J seems not to build with OSGi in mind, hence the misleading warning Class path contains multiple SLF4J bindings, although there is no classpath in OSGi which uses its own class loader instead.

Upvotes: 3

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