ClassNotFoundException，同时运行Hadoop的示例作业 [英] ClassNotFoundException, while running example job of Hadoop

问题描述

我已经在hadoop上开始了一些小东西。它的设置和运行正常。现在我正在做一个单独的节点/独立群集。
我尝试运行示例作业，如 http：/ /hadoop.apache.org/common/docs/r0.18.3/mapred_tutorial.html

到目前为止，程序编译正确，jar已经创建，清单添加成功。但是当我尝试运行这个工作时，出现这个错误。

 线程main中的异常java.lang.ClassNotFoundException：org .myorg.WordCount在java.net.URLClassLoader上
 $ 1.run（URLClassLoader.java:202）在java.security.AccessController.doPrivileged上的
（本地方法）$在java.net.URLClassLoader上
 .findClass（URLClassLoader.java:190）$ b $在java.lang.ClassLoader.loadClass（ClassLoader.java:306）
在java.lang.ClassLoader.loadClass（ClassLoader.java:247）
在java.lang.Class.forName0（本地方法）$ b $在java.lang.Class.forName（Class.java:247）
在org.apache.hadoop.util.RunJar.main（RunJar .java：149）
  

我有复制粘贴与链接中提到的完全相同的程序。但它给了这个错误。这是我打的命令行。

  [shantanu @ shades1ld1 hadoop] $ bin / hadoop jar /home/shantanu/hadoop/src/examples/wordcount.jar org .myorg.WordCount / tmp / Hadoop_Jobs / / tmp / Hadoop_Results 
  

我已经阅读了大量文章，但找不到解释，请帮忙。

包含 org.myorg.WordCount 类？

您没有修改包名？

I have started a little something on hadoop. It is setup and running properly. Right now I am doing a single node / stand alone cluster. I am trying to run sample job as mentioned on http://hadoop.apache.org/common/docs/r0.18.3/mapred_tutorial.html

So far, program is correctly compiled, jar has been created, manifest added successfully. But when I try to run the job I get this error.

Exception in thread "main" java.lang.ClassNotFoundException: org.myorg.WordCount
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 java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:247)
at org.apache.hadoop.util.RunJar.main(RunJar.java:149)

I have copy pasted the exact same program as mentioned in link. But it's giving this error. This is the command line I hit.

[shantanu@shades1ld1 hadoop]$ bin/hadoop jar /home/shantanu/hadoop/src/examples/wordcount.jar org.myorg.WordCount /tmp/Hadoop_Jobs/ /tmp/Hadoop_Results

I have gone through numerous articles, but couldn't find an explanation for this, please help.

解决方案

Are you sure that wordcount.jar contains the org.myorg.WordCount class?

Didn't you modify the package name?

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