SLF4J: Failed to load class “org.slf4j.impl.Static

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• SLF4J: Failed to load class “org.slf4j.impl.StaticLoggerBinder”. error 9 answers

I have a dependency for SLF4J. 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.

Here is my maven entry:

    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.6.6</version>
    </dependency>

    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>1.6.6</version>
    </dependency>
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.16</version>
    </dependency>

Where is the problem?

---

EDIT: Without log4j dependency I get the following exception

Failed to instantiate SLF4J LoggerFactory
Reported exception:
java.lang.NoClassDefFoundError: org.slf4j.impl.StaticLoggerBinder
    at org.slf4j.LoggerFactory.bind(LoggerFactory.java:121)
    at org.slf4j.LoggerFactory.performInitialization(LoggerFactory.java:111)
    at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:268)
    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:241)
    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:254)
    at org.apache.bval.jsr303.ConfigurationImpl.<clinit>(ConfigurationImpl.java:50)
    at java.lang.J9VMInternals.initializeImpl(Native Method)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:228)
    at org.apache.bval.jsr303.ApacheValidationProvider.createGenericConfiguration(ApacheValidationProvider.java:66)
    at javax.validation.Validation$GenericBootstrapImpl.configure(Validation.java:173)
    at javax.validation.Validation.buildDefaultValidatorFactory(Validation.java:50)
    at com.daimler.zv9.basic.entity.AbstractEntity.<clinit>(AbstractEntity.java:73)
    at java.lang.J9VMInternals.initializeImpl(Native Method)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:228)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:195)
    at java.lang.Class.forNameImpl(Native Method)
    at java.lang.Class.forName(Class.java:168)

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EDIT2: It is an example MAVEN Tree that I get

[INFO] com.myCompany.abc:ABC_Document:ejb:0.0.1-SNAPSHOT
[INFO] +- com.myCompany.abc:ABC_Basic:jar:0.0.1-SNAPSHOT:compile
[INFO] +- com.myCompany.iap:javax.j2ee:jar:5.0.0:provided
[INFO] +- com.myCompany.iap:logging:jar:5.0.0:provided
[INFO] +- com.myCompany.iap:util:jar:5.0.0:provided
[INFO] +- junit:junit:jar:4.8.2:test
[INFO] +- javax.servlet:jstl:jar:1.2:provided
[INFO] +- org.slf4j:slf4j-api:jar:1.6.6:compile
[INFO] +- org.slf4j:slf4j-simple:jar:1.6.6:compile
[INFO] \- org.mockito:mockito-all:jar:1.9.0:test

Answer 1

Remove

<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.16</version>
</dependency> 

slf4j-log4j12 is the log4j binding for slf4j you dont need to add another log4j dependency.

Added
Provide the log4j configuration in log4j.properties and add it to your class path. There are sample configurations here

or you can change your binding to

<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-simple</artifactId>
    <version>1.6.1</version>
</dependency>

if you are configuring slf4j due to some dependencies requiring it.

Answer 2

I ran into this in IntelliJ and fixed it by adding the following to my pom:

<!-- logging dependencies -->
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>${logback.version}</version>
        <exclusions>
            <exclusion>
                <!-- Defined below -->
                <artifactId>slf4j-api</artifactId>
                <groupId>org.slf4j</groupId>
            </exclusion>
        </exclusions>
    </dependency>

    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>${slf4j.version}</version>
    </dependency>

Answer 3

The message you mention is quite clear:

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.

SLF4J API could not find a binding, and decided to default to a NOP implementation. In your case slf4j-log4j12.jar was somehow not visible when the LoggerFactory class was loaded into memory, which is admittedly very strange. What does "mvn dependency:tree" tell you?

The various dependency declarations may not even be directly at cause here. I strongly suspect that a pre-1.6 version of slf4j-api.jar is being deployed without your knowledge.

Answer 4

I am assuming you are using Eclipse as your developing environment.

Eclipse Juno, Indigo and Kepler 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 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 which i believe describes the same problem you are facing.

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