Hadoop - Mapreduce - java.lang.NoClassDefFoundError:

I am working with Eclipse. After adding a file to the Hadoop distributed cache (found the howto on this LINK) I received the error message:

INFO: Cached file:///home/aatmaca/git/common/rules.txt as /tmp/hadoop-root/mapred/local/archive/-5239344160850859454_-776894720_2117948037/file/home/git/common/rules.txt
14.11.2012 11:59:08 org.apache.hadoop.mapred.JobClient$2 run
INFO: Cleaning up the staging area file:/tmp/hadoop-root/mapred/staging/root-542082906/.staging/job_local_0001
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/io/FileUtils 
at org.apache.hadoop.fs.FileUtil.getDU(FileUtil.java:456)
at org.apache.hadoop.filecache.TrackerDistributedCacheManager.downloadCacheObject(TrackerDistributedCacheManager.java:452)
at org.apache.hadoop.filecache.TrackerDistributedCacheManager.localizePublicCacheObject(TrackerDistributedCacheManager.java:464)

I was sure that this is not a hadoop specific problem. A simple import of org.apache.commons.io.FileUtils didnt do the trick ( yes I'm still new to this Java stuff :) ), so I had to ask my Coding mentor for help..

Solution 1:

Download the latest commons-io JAR from:
http://mvnrepository.com/artifact/commons-io/commons-io/

Within Eclipse:
Right click on project -> Properties -> Build Path -> Add External JARs..
and import your JAR file. It should appear now within your "Referenced Libraries" folder.

Now you should be able to execute the application without error messages.

Solution 2:

If it is a Maven project you are working on, just edit your .pom file and add the common-io dependency to it:

        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.4</version>
        </dependency>

Sources will be downloaded automatically and added to your Maven dependencies..

Good luck!