上面列出的解决方案没有一个对我有效。

这就是我遇到的问题:

I added the jSoup external JAR file to my project's path by first putting it in a source folder called "libs", and then right clicking on it, Build Path -> add to build path. This threw the Dalvik conversion error. It said I had "already included" a class from that JAR file. I looked around the project's directory and found that the place where it was "already included" was in fact the bin directory. I deleted the JAR file from the bin directory and refreshed the project in Eclipse and the error went away!

这里的答案对我的情况没有帮助。

对我来说，问题是mvn eclipse:eclipse正在生成一个类路径条目，这是一个Android库项目的项目引用，然而，它没有显示在eclipse构建路径设置!这意味着库类在dexer中结束了两次，一次来自隐藏的项目引用，一次来自链接库JAR。

我必须用文本编辑器打开.classpath并手动删除projects元素。这解决了问题。

对我来说

项目->属性->java build path -> in order and export TAB ->取消选中android-support-v4.jar

下面是另一个场景和解决方案:

如果您最近在更新Eclipse ADT后遇到这个问题:

在你的应用项目中，检查任何指向你的库项目的链接源文件夹(它们的名称以“LibraryName_src”的形式存在)。 选择所有这些项目，右键单击，选择“构建路径”->“从构建路径中删除”。 选择“也从项目中取消该文件夹的链接”，然后单击“是”。 清理、重新构建和重新部署项目。

原因似乎是ADT以前的一些版本将库项目源文件夹链接到“子”项目，而当前ADT/Dex组合不再与该解决方案兼容。

编辑:这一点在Android开发博客的一篇文章中得到了证实，特别是这篇文章——见第8段。

我也遇到过同样的问题，但这些方法都不起作用。 最后，我在控制台中看到错误是由于重复的类(一个在现有项目中，一个在添加的jar文件中):

java.lang.IllegalArgumentException: already added: package/MyClassclass;
[2011-01-19 14:54:05 - ...]: Dx1 error; aborting
[2011-01-19 14:54:05 - ...] Conversion to Dalvik format failed with error 1

因此，请检查您是否在项目中添加了带有重复类的jar。 如果是，请尝试移除其中一个。

这对我很管用。

上面列出的解决方案没有一个对我有效。

这就是我遇到的问题:

I added the jSoup external JAR file to my project's path by first putting it in a source folder called "libs", and then right clicking on it, Build Path -> add to build path. This threw the Dalvik conversion error. It said I had "already included" a class from that JAR file. I looked around the project's directory and found that the place where it was "already included" was in fact the bin directory. I deleted the JAR file from the bin directory and refreshed the project in Eclipse and the error went away!