main java lang ClassNotFoundException WordCount

Question

When I am run the jar of wordcount using this command:

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

it always shows this 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)

This is a simple program but I am not able to run. I have not made any changes. Please help me solve this.

Answer 1

When you are running a jar file in Hadoop, you have to mention the whole package name. The syntax is as follows:

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