title: How to fix exception: Failed to instantiate SLF4J LoggerFactory?
body: <p>I am trying to write a java web crawler for semantic web using jena library. I have build project using Netbeans. I am receiving two errors:</p>
  
  <ol>
  <li><p>Failed to instantiate SLF4J LoggerFactory
  Reported exception:
  java.lang.NoClassDefFoundError: org/apache/log4j/Level</p></li>
  <li><p>Could not initialize class com.hp.hpl.jena.rdf.model.impl.ModelCom
  at org.slf4j.LoggerFactory.bind(LoggerFactory.java:128)</p></li>
  </ol>
  
  <p>I have included <code>slf4j-api</code> and <code>slf4j-log</code> both libraries.</p>