Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/hadoop/util/Tool

Question

I get below error when i package (jar) and run my defaulthadoopjob. 

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/hadoop/util/Tool
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
Caused by: java.lang.ClassNotFoundException: org.apache.hadoop.util.Tool
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
    ... 12 more
Could not find the main class: DefaultHadoopJobDriver. Program will exit.


Commands used to build Jar. 

# jar -cvf dhj.jar 
# hadoop -jar dhj.jar DefaultHadoopJobDriver

The above command gave me error "Failed to load Main-Class manifest attribute from dhj.jar"

rebuilt jar with manifest using below command

jar -cvfe dhj.jar DefaultHadoopJobDriver .
hadoop -jar dhj.jar DefaultHadoopJobDriver -- This returned the original error message that I reported above.

My Hadoop job has single class "DefaultHoopJobDrive" that extends Configures and implements Tool, and run method as only code for Job creation and inputpath,outpurpath set. Aslo I.m using new API.

I'm running hadoop 1.2.1 and the Job works fine from eclipse.

This might be something to do with the classpath. Please help.

Answer 1

For executing that jar you don't have to give hadoop -jar. The command is like so:

 hadoop jar <jar> [mainClass] args...

If this jar again gets the java.lang.ClassNotFoundException exception then can you use the:

hadoop classpath

command to see whether hadoop-core-1.2.1.jar is present in your hadoop installations classpath?

FYI, and if it's not present in this list you have to add this jar to the hadoop lib directory.