Exception thrown while using logback/slf4j

Question

I am using slf4j 1.6.2 api jar (tried using 1.6.1 as well) - logback version is 0.9.29 (core & classic). I am using jdk1.6 on ubuntu. The exception I received is copied

Answer 1

Download from Below link

https://jar-download.com/artifacts/ch.qos.logback/logback-classic/1.1.3/source-code

all three jars are compatible with each other