title: Java Errors starting from ClassNotFoundException
body: <p>I have the following errors when i try to run my Netbeans aplication of a map reduce algorithm:</p>
  
  <pre><code>Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/log4j/Level
  at org.apache.hadoop.mapred.JobConf.&lt;clinit&gt;(JobConf.java:349)
  at java.lang.Class.forName0(Native Method)
  at java.lang.Class.forName(Class.java:264)
  at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:1121)
  at org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:88)
  at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:72)
  at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:125)
  at org.apache.hadoop.security.Groups.&lt;init&gt;(Groups.java:54)
  at org.apache.hadoop.security.Groups.getUserToGroupsMappingService(Groups.java:142)
  at     
  org.apache.hadoop.security.UserGroupInformation.initUGI(UserGroupInformation.java:243)
  at 
  org.apache.hadoop.security.UserGroupInformation.initialize(UserGroupInformation
  .java:216)
  at     
  org.apache.hadoop.security.UserGroupInformation.ensureInitialized(UserGroupInformation
  .java:207)
  at   
  org.apache.hadoop.security.UserGroupInformation.isSecurityEnabled(UserGroup
  Information.java:286)
  at org.apache.hadoop.security.UserGroupInformation.getLoginUser(UserGroup
  Information.java:500)
  at org.apache.hadoop.security.UserGroupInformation.getCurrentUser(UserGroup   
  Information.java:483)
  at org.apache.hadoop.mapreduce.Cluster.&lt;init&gt;(Cluster.java:73)
  at org.apache.hadoop.mapreduce.Job.&lt;init&gt;(Job.java:133)
  at org.apache.hadoop.mapreduce.Job.&lt;init&gt;(Job.java:138)
  at cloudex.CloudEx.main(CloudEx.java:33)
  Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Level
  at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
  at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
  at java.security.AccessController.doPrivileged(Native Method)
  at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
  at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
  ... 19 more
  </code></pre>
  
  <p>Could you please give me a hint on how to get rid of it? i do not know what it generates it</p>