Eclipse MapReduce错误：UnModifiableMap

Question

so I'm new to Hadoop and MapReduce and am attempting to create a simple WordCount program. When running it however, I run into an error:

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/collections/map/UnmodifiableMap
at org.apache.hadoop.conf.Configuration$DeprecationContext.<init>(Configuration.java:409)
at org.apache.hadoop.conf.Configuration.<clinit>(Configuration.java:448)
at com.Cameron.WordCount.main(WordCount.java:51)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.collections.map.UnmodifiableMap
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
... 3 more

I've had a look around online and the cause seems to be the fact that the Commons Collection JAR isn't included in the build path, although with mine it is and I'm still getting the error. I've tried cleaning the project and restarting Eclipse to no avail, so any help would be greatly appreciated. My build path configuration is as follows:

commons-collections4-4.1.jar
commons-lang-2.6.jar
commons-logging-1.2.jar
guava-11.0.2.jar
hadoop-common-2.7.2.jar
hadoop-mapreduce-client-core-2.7.2.jar
JRE System Library [JavaSE-1.7]

Answer 1

I have run into a similar error. I am running through a tutorial on cloudera 5.8 using luna eclipse ( https://github.com/hortonworks/hadoop-tutorials/blob/master/Community/T09_Write_And_Run_Your_Own_MapReduce_Java_Program_Poll_Result_Analysis.md ).

You need Apache Commons Collections » 3.2.1 (NOT 4.1), add it to your build path and it should run.