我知道这个问题已经很多次，但相信我，我都检查过了。大部分的问题都表明，除去导入android.R，在XML文件中删除任何错误，检查文件（没有大写字母）的名称，然后重建和清理项目或重新启动Eclipse 。我已经尝试了所有，但没有解决问题。 问题发生时，我打扫的所有项目。现在所有的项目都出现了这个错误。由于所有的项目都运行完美之前，我清理项目，也不可能所有的突然布局或所有项目的文件名，在其中有错误。

I know this question has been many times but trust me I have checked all. Most of the question suggests to remove import android.R , remove any error in the xml file, checking name of the files (no capital letters) then rebuild and clean the project or restart eclipse. I have tried all but none solved the problem. The problem occured when i cleaned all the projects. Now all the projects are showing that error. Since all the project were running perfectly before i cleaned projects, there is no possibility that all of the sudden the layouts or the file names of all the projects have error in them.

也有是在没有文件根文件夹。至于我能理解有一些错误的构建路径或 preferences 可以anyne点我一个正确的方向吗？ ！

Also there is no file in gen folder. As far as i can understand there is something wrong with the build path or preferences can anyne point me in a correct direction? !

推荐答案

请确保你安装了 Android编译工具形式SDK管理器

Make sure you installed the Android build tool form sdk manager

项目右键属性 - > Java的构建路径选择库，并添加 Android的support.jar 的请按照下列步骤。

project right click properties-> Java BuildPath select Library and add android-support.jar the follow these step.

转到项目 - >属性 - >比选择订单和出口标签的Java构建路径。设置 Android的支持的.jar 库检查，向上成名列榜首。而清洁rebuild..It适用于大多数的情况下，

Go to Project->Properties->Java Build Path than select Order and export tab. Set android-support .jar library checked and up it into top of the list. And clean and rebuild..It works for most of the cases