windows Weka no main class found 错误
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Weka no main class found error
提问by kamikaze_pilot
I installed the latest version of Weka on Windows
我在 Windows 上安装了最新版本的 Weka
http://www.cs.waikato.ac.nz/ml/weka/
http://www.cs.waikato.ac.nz/ml/weka/
and I tried to run one of the weka features from the command line:
我尝试从命令行运行其中一项 weka 功能：
java weka.core.converters.TextDirectoryLoader -dir text_example > text_example.arff
which is a reference to this: http://weka.wikispaces.com/Text+categorization+with+WEKA
这是对此的参考：http: //weka.wikispaces.com/Text+categorization+with+WEKA
but then weka returns this error:
但随后 weka 返回此错误：
Microsoft Windows [Version 6.1.7600]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.
Exception in thread "main" java.lang.NoClassDefFoundError: weka/core/converters/
TextDirectoryLoader
Caused by: java.lang.ClassNotFoundException: weka.core.converters.TextDirectoryL
oader
at java.net.URLClassLoader.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
Could not find the main class: weka.core.converters.TextDirectoryLoader. Progra
m will exit.
I already set the CLASSPATH environment variable to point to the weka jar.
我已经将 CLASSPATH 环境变量设置为指向 weka jar。
What did I do wrong?
我做错了什么？
回答by ahans
The shell you run the command in apparently doesn't have the CLASSPATH environment variable set properly, otherwise the ClassNotFoundException wouldn't occur. As an alternative to the environment variable you can specify the classpath using the command line:
您在其中运行命令的 shell 显然没有正确设置 CLASSPATH 环境变量，否则不会发生 ClassNotFoundException。作为环境变量的替代方案，您可以使用命令行指定类路径：
java -cp path/to/weka.jar weka.core.converters.TextDirectoryLoader -dir [...]
You can also check whether the environment variable is set correctly by executing echo %CLASSPATH%in the cmd shell.
也可以通过echo %CLASSPATH%在cmd shell中执行来检查环境变量是否设置正确。
