类未找到异常hadoop

Question

Hi i am running map reduce word count in hadoop.I am getting this error.

Exception in thread "main" java.lang.ClassNotFoundException: -files
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 java.lang.ClassLoader.loadClass(ClassLoader.java:358)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:270)
at org.apache.hadoop.util.RunJar.main(RunJar.java:205)

But when i export as runnable jar it is working.But when i trying through maven.it is not working.Please help to resolve the issue.

Answer 1

When you export you jar as runnable jar the main class of your application is defined in the manifest. If you start it from maven you have to define your main class. The exception you show means that The run method expects a class as parameter whereas you defined "-files". So just add the full qualified name of your main class of your mapreduce job before "-files" and it should work.

Edit: See documentation for an example. The command will look like the following line.

hadoop jar myjar.jar com.mycompany.task.Main -files ...