Java – HADOOP::java.lang.ClassNotFoundException:WordCount

I’m using Eclipse to export the JAR file for the Map-Reduce program. When I run jar with the command

 hadoop jar hadoop-prog.jar WordCount /home/temp/input /home/temp/output

It always shows the error:

   Exception in thread "main" java.lang.ClassNotFoundException: WordCount
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:247)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:149)

By the way, I got a wordcount example jar file from the internet and it works just fine.

I can’t think of a problem.

If you try to run the word count provided in the example, you should run:

hadoop jar hadoop*examples*.jar wordcount /home/temp/input /home/temp/output

How to use this in More information on running wordcount on this link

In general, if you’re developing your own Map/Reduce job, you should include the full package name of your driver class, so something like this might work:

hadoop jar wordcount.jar com.something.WordCount /home/temp/input /home/temp/output