SLF4J: slf4j-api 1.6.x (or later) is incompatible with this binding

Question

2015-09-28 10:02:21,890 ERROR [STDERR] (HDScanner) SLF4J: slf4j-api 1.6.x (or later) is incompatible with this binding. 2015-09-28 10:02:21,891 ERROR [STDERR] (HDScanner) SLF4J: Your binding is version 1.5.5 or earlier. 2015-09-28 10:02:21,891 ERROR [STDERR] (HDScanner) SLF4J: Upgrade your binding to version 1.6.x. 2015-09-28 10:02:21,891 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/metasolv-web]] (HDScanner) Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener java.lang.NoSuchMethodError: org.slf4j.impl.StaticLoggerBinder.getSingleton()Lorg/slf4j/impl/StaticLoggerBinder; 

How to fix this error? Also, in my application, I do not use slf4j anywhere, only the Dozer library uses it. from the underlying stacktrace, I see that the spring application uses slf4j, but why doesn't it load it on its own?

 java.lang.NoSuchMethodError: org.slf4j.impl.StaticLoggerBinder.getSingleton()Lorg/slf4j/impl/StaticLoggerBinder; at org.slf4j.LoggerFactory.bind(LoggerFactory.java:128) at org.slf4j.LoggerFactory.performInitialization(LoggerFactory.java:107) at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:295) at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:269) at org.apache.commons.logging.impl.SLF4JLogFactory.getInstance(SLF4JLogFactory.java:156) at org.apache.commons.logging.impl.SLF4JLogFactory.getInstance(SLF4JLogFactory.java:132) at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:645) at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:191) 

Answer 1

I had to exclude slf4j depenedencies from the dozer library and add dependencies directly to the POM file.

As @Powerlord already mentioned, I had to add two libraries, one for the slf4j core, and the other a binding library.

The following are Maven dependencies.

  <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>1.6.6</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-simple</artifactId> <version>1.6.6</version> </dependency> <dependency> <groupId>net.sf.dozer</groupId> <artifactId>dozer</artifactId> <version>5.5.1</version> <exclusions> <exclusion> <artifactId>jcl-over-slf4j</artifactId> <groupId>org.slf4j</groupId> </exclusion> <exclusion> <artifactId>slf4j-api</artifactId> <groupId>org.slf4j</groupId> </exclusion> </exclusions> </dependency> 

Answer 2

SLF4J is statically related based on dependency.

If you use log4j, you must have log4j binding in your application.

Even if you are not using slf4j, you will need a binding (simple or noop) to make it load correctly from the dependent library.