Java错误，java.lang.NoClassDefFoundError：Hadoop中的org / myorg / WordCount

Question

I'm very new to Hadoop. I followed the basic tutorial about how to create word count program in hadoop. Everything was fine. I than tried to create my own map reduce, and put it in a separate jar file. When I tried to run the program, it gives me that error:

shean@ubuntu-PC:~/hadoop/bin$ hadoop jar ../weather.jar weather.Weather /user/hadoop/weather_log_sample.txt /user/hadoop/output
Warning: $HADOOP_HOME is deprecated.

Exception in thread "main" java.lang.NoClassDefFoundError: org/myorg/WordCount
    at weather.Weather.main(Weather.java:45)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:616)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:156)
Caused by: 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)
    ... 6 more

But the problem is , it's looking for WordCount class...

Answer 1

如果我没记错的话，您会错过jar wordcount.jar 。请将其添加到build path.

Answer 2

My advice: you put "package" path first removed. This makes it easier not reported NoClassDefFoundError errors. javac compile time: javac-classpath "$ HADOOP_HOME/hadoop-core-1.2.0.jar: $ HADOOP_HOME/lib/commons-cli-1.2.jar"-d. / weather

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