Failed to load class "org.slf4j.impl.StaticLoggerBinder" -- Which classpath?

Question

My pom.xml contains only one reference to SLF4J:

    <dependency>         <groupId>org.slf4j</groupId>         <artifactId>slf4j-jdk14</artifactId>         <version>1.5.10</version>     </dependency> 

I am getting this error:

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".

SLF4J: Defaulting to no-operation (NOP) logger implementation SLF4J:

See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.

I checked that URL and indeed it provides a solution: "Placing one (and only one) of slf4j-nop.jar, slf4j-simple.jar, slf4j-log4j12.jar, slf4j-jdk14.jar or logback-classic.jar on the class path should solve the problem. "

My question is: which classpath?

• The system's %CLASSPATH%? (I don't have one! I will need to create it specifically for this)
• Eclipse's project .classpath? (I think I tried this but it didn't help)
• Other?

I found quite a few postings on the subject here on SO, but they all quote the same answer: "place ... on the class path".

Which classpath?

Answer 1

First of all in order to add SLF4J you should put ONE and only ONE of these dependencies in your pom.xml. It depends on what implementation you choose to use. Every dependency you add in the pom.xml is added automatically in the classpath. As long as you are using Eclipse there is no need to modify the system's %CLASSPATH%?

<dependency>    <groupId>ch.qos.logback</groupId>    <artifactId>logback-classic</artifactId>    <version></version> </dependency> 

<dependency>    <groupId>org.slf4j</groupId>    <artifactId>slf4j-simple</artifactId>    <version></version>    <scope>compile</scope> </dependency> 

<dependency>    <groupId>org.slf4j</groupId>    <artifactId>slf4j-log4j12</artifactId>    <version></version>    <scope>compile</scope> </dependency> 

<dependency>    <groupId>org.slf4j</groupId>    <artifactId>slf4j-jdk14</artifactId>    <version></version>    <scope>compile</scope> </dependency> 

Last but not least you will have the error SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".

Eclipse Juno and Indigo, when using the bundled maven version(m2e), are not suppressing the message SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder". This behaviour is present from the m2e version 1.1.0.20120530-0009 and onwards.

Although, this is indicated as an error your logs will be saved normally. The highlighted error will still be present until there is a fix of this bug. More about this in the m2e support site.

The current available solution in order to suppress this message is to use an external maven version rather than the bundled version of Eclipse. You can find about this solution and more details regarding this bug in the question below.

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder". error