SLF4J version conflict

Here are the exception details.

Exception in thread "main" java.lang.IllegalAccessError: tried to access field
org.slf4j.impl.StaticLoggerBinder.SINGLETON from class org.slf4j.LoggerFactory
   at org.slf4j.LoggerFactory.<clinit>(LoggerFactory.java:60)

This error is caused by the static initilizer of the LoggerFactory class attempting to directly access the SINGLETON field oforg.slf4j.impl.StaticLoggerBinder. While this was allowed in SLF4J 1.5.5 and earlier, in 1.5.6 and later the SINGLETON field has been marked as private access.

If you get the exception shown above, then you are using an older version of slf4j-api, e.g. 1.4.3, with a new version of a slf4j binding, e.g. 1.5.6. Typically, this occurs when your Maven pom.ml file incoprporates hibernate 3.3.0 which declares a dependency on slf4j-api version 1.4.2. If yourpom.xml declares a dependency on an slf4j binding, say slf4j-log4j12 version 1.5.6, then you will get illegal access errors.

To see which version of slfj4-api is pulled in by Maven, use the maven dependency plugin as follows.

mvn dependency:tree

If you are usig Eclipse, please do not rely on the dependency tree shown by m2eclipse.

In your pom.xml file, excplicitly declaring a dependecy on slf4j-api matching the version of the declared binding will make the problem go away.