即使在官方教程上也出现 GWT 错误 : Check that your module inherits 'com.google.gwt.core.Core' either directly or indirectly

Question

我正在学习 GWT 并尝试运行 this tutorial Vogella 和 official GWT tutorial .

在 Windows 10 和 JDK 11 上使用 Eclipse GWT 插件 3.0

我标记了 Maven Project 复选框。

当我右键单击并运行为

Turning off precompile in incremental mode.
Super Dev Mode starting up
   workDir: C:\Users\My\AppData\Local\Temp\gwt-codeserver-8137229043727681777.tmp
2021-04-29 12:03:13.494:INFO::main: Logging initialized @718ms
   Loading Java files in de.vogella.gwt.helloworld.De_vogella_gwt_helloworld.
   [ERROR] Hint: Check that your module inherits 'com.google.gwt.core.Core' either directly or indirectly (most often by inheriting module 'com.google.gwt.user.User')

我看到是继承了User

<?xml version="1.0" encoding="UTF-8"?>
<!--
  When updating your version of GWT, you should also update this DTD reference,
  so that your app can take advantage of the latest GWT module capabilities.
-->
<!DOCTYPE module PUBLIC "-//Google Inc.//DTD Google Web Toolkit 2.8.1//EN"
  "http://www.gwtproject.org/doctype/2.8.1/gwt-module.dtd">
<module rename-to='de_vogella_gwt_helloworld'>
  <!-- Inherit the core Web Toolkit stuff.                        -->
  <inherits name='com.google.gwt.user.User'/>

  <!-- Inherit the default GWT style sheet.  You can change       -->
  <!-- the theme of your GWT application by uncommenting          -->
  <!-- any one of the following lines.                            -->
  <inherits name='com.google.gwt.user.theme.clean.Clean'/>
  <!-- <inherits name='com.google.gwt.user.theme.standard.Standard'/> -->
  <!-- <inherits name='com.google.gwt.user.theme.chrome.Chrome'/> -->
  <!-- <inherits name='com.google.gwt.user.theme.dark.Dark'/>     -->

  <!-- Other module inherits                                      -->

  <!-- Specify the app entry point class.                         -->
  <entry-point class='de.vogella.gwt.helloworld.client.De_vogella_gwt_helloworld'/>

  <!-- Specify the paths for translatable code                    -->
  <source path='client'/>
  <source path='shared'/>

  <!-- allow Super Dev Mode -->
  <add-linker name="xsiframe"/>
</module>

这SO question与我的问题无关。

Answer 1

几乎可以肯定，您要么在类路径中缺少 gwt-user.jar，要么 gwt-user.jar 版本与 gwt-dev.jar 不匹配，这会导致问题。每个模块都会自动继承 com.google.gwt.core.Core(尽管有错误消息)，并且如您的 .gwt.xml 所示，您已经添加了用户。

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此外，从您链接的 SO 帖子中，请检查评论 - 列出了一些更好、更现代的教程。