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MapReduce, mail # user - ClassNotFoundException in Main


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Re: ClassNotFoundException in Main
Hemanth Yamijala 2013-02-19, 16:02
Have you used the Api setJarByClass in your main program?

http://hadoop.apache.org/docs/r1.0.4/api/org/apache/hadoop/mapreduce/Job.html#setJarByClass(java.lang.Class)

On Tuesday, February 19, 2013, Fatih Haltas wrote:

> Hi everyone,
>
> I know this is the common mistake to not specify the class adress while
> trying to run a jar, however,
> although I specified, I am still getting the ClassNotFound exception.
>
> What may be the reason for it? I have been struggling for this problem
> more than a 2 days.
> I just wrote different MapReduce application for some anlaysis. I got this
> problem.
>
> To check, is there something wrong with my system, i tried to run
> WordCount example.
> When I just run hadoop-examples wordcount, it is working fine.
>
> But when I add just "package org.myorg;" command at the beginning, it
> doesnot work.
>
> Here is what I have done so far
> *************************************************************************
> 1. I just copied wordcount code from the apaches own examples source code
> and I just changed package decleration as "package org.myorg;"
> **************************************************************************
> 2. Then I tried to run that command:
>  *************************************************************************
> "hadoop jar wordcount_19_02.jar org.myorg.WordCount
> /home/hadoop/project/hadoop-data/NetFlow 19_02_wordcount.output"
> *************************************************************************
> 3. I got following error:
> **************************************************************************
> [hadoop@ADUAE042-LAP-V project]$ hadoop jar wordcount_19_02.jar
> org.myorg.WordCount /home/hadoop/project/hadoop-data/NetFlow
> 19_02_wordcount.output
> Warning: $HADOOP_HOME is deprecated.
>
> Exception in thread "main" java.lang.ClassNotFoundException:
> org.myorg.WordCount
>         at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
>         at java.security.AccessController.doPrivileged(Native Method)
>         at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
>         at java.lang.Class.forName0(Native Method)
>         at java.lang.Class.forName(Class.java:266)
>         at org.apache.hadoop.util.RunJar.main(RunJar.java:149)
>
> **************************************************************************
> 4. This is the content of my .jar file:
> ****************************************************
> [hadoop@ADUAE042-LAP-V project]$ jar tf wordcount_19_02.jar
> META-INF/
> META-INF/MANIFEST.MF
> wordcount_classes/
> wordcount_classes/org/
> wordcount_classes/org/myorg/
> wordcount_classes/org/myorg/WordCount.class
> wordcount_classes/org/myorg/WordCount$TokenizerMapper.class
> wordcount_classes/org/myorg/WordCount$IntSumReducer.class
> **********************************************************
> 5. This is the 'ls' output of my working directory:
> **********************************************************
> [hadoop@ADUAE042-LAP-V project]$ ls
> flowclasses_18_02  flowclasses_18_02.jar  hadoop-1.0.4
>  hadoop-1.0.4.tar.gz  hadoop-data  MapReduce.java  sample
>  wordcount_19_02.jar  wordcount_classes  WordCountClasses  WordCount.java
> *************************************************************
> So as you see, package decleration is fine but I am really helpless, I
> googled but they are all saying samething you should specify the package
> hierarchy of your main class. I did know it already I am specifying but
> doesn't work.
>
> I would be much obliged to anyone helped me
>
> Regards,
>
>
>