Apache Flink的WordCount示例 - "main"线程中的异常：java.lang.NoClassDefFoundError：org/apache/flink/api/common/functions/FlatMapFunction

Question

我按照这个指南操作，但是如果我在我的IDE中运行WordCount，则会出现异常

/usr/lib/jvm/java-8-oracle/bin/java -Didea.launcher.port=7536 -Didea.launcher.bin.path=/home/marc/Programs/idea-IC-162.2032.8/bin -Dfile.encoding=UTF-8 -classpath "/usr/lib/jvm/java-8-oracle/jre/lib/charsets.jar:/usr/lib/jvm/java-8-oracle/jre/lib/deploy.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/cldrdata.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/dnsns.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/jaccess.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/jfxrt.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/localedata.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/nashorn.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/sunec.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/sunjce_provider.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/sunpkcs11.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/zipfs.jar:/usr/lib/jvm/java-8-oracle/jre/lib/javaws.jar:/usr/lib/jvm/java-8-oracle/jre/lib/jce.jar:/usr/lib/jvm/java-8-oracle/jre/lib/jfr.jar:/usr/lib/jvm/java-8-oracle/jre/lib/jfxswt.jar:/usr/lib/jvm/java-8-oracle/jre/lib/jsse.jar:/usr/lib/jvm/java-8-oracle/jre/lib/management-agent.jar:/usr/lib/jvm/java-8-oracle/jre/lib/plugin.jar:/usr/lib/jvm/java-8-oracle/jre/lib/resources.jar:/usr/lib/jvm/java-8-oracle/jre/lib/rt.jar:/home/marc/apache flink/flink.gelly/target/classes:/home/marc/Programs/idea-IC-162.2032.8/lib/idea_rt.jar" com.intellij.rt.execution.application.AppMain haw.bachelor.flink.gelly.WordCount
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/flink/api/common/functions/FlatMapFunction
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:264)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:123)
Caused by: java.lang.ClassNotFoundException: org.apache.flink.api.common.functions.FlatMapFunction
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 3 more

我的环境：

• Ubuntu 14.04 LTS
• Oracle Java 8
• Maven 3.0.5
• IntelliJ社区版

- mKaepke

Answer 1

以下是我更改的设置，错误已被解决

- huang botao

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在我的情况下起了作用。谢谢。 - Shahnur Isgandarli

Answer 2

在Intellij IDEA（2020.3）中，用户界面有所不同。

步骤：

1. 激活“运行配置”下拉菜单 2. 点击“编辑配置...” 3. 点击“修改选项” 4. 选择“包括提供的作用域依赖项” 5. 点击“完成”

现在应该已经包含Flink源代码，并且应该解决了遇到的错误 - 对我来说确实如此！

- Chris Trahey

Answer 3

如果您在IDE中运行它，必须从“运行配置”菜单中选择“mainRunner”而不是“root”。这将使类路径加载项目中“提供”的类。

- Chobeat

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请问您有时间能否分享一下在IntelliJ中如何操作的屏幕截图？ - sri hari kali charan Tummala

Answer 4

我通过在IDE中停用Maven中的“build-jar”配置文件来解决了这个问题。似乎关闭它将使运行时类可用。

- Ahmad Eldefrawy

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请问您能分享一下在IntelliJ IDEA中如何操作的屏幕截图吗？ - sri hari kali charan Tummala