“无法解析符号R”在Android Studio

In every instance in all of my classes where I reference R.id.something, the R is in red and it says "cannot resolve symbol R". Also every time there is R.layout.something it is underlined in red and says "cannot resolve method setContentView(?)". The project always builds fine. It is annoying to see this all the time. I have read many other questions on here about something similar but most involved importing projects from Eclipse. I am using what I believe to be the most recent version of Android Studio and the project was created with Android Studio and worked without any "cannot resolve R" problems. I would like to know what causes this if anyone knows.

当前回答

清洁，重建和“缓存删除”不会帮助我，更新Android工作室修复了这个问题。

2019-01-16 16:41:49

其他回答

“我也遇到过同样的问题，解决方法是:

1) Sync Project with gradle files
2) Build -> Clean Project
3) Build -> Rebuild Project
4) File -> Invalidate caches

//imp step
5) Check your xml files properly.`

2017-09-19 05:46:16

在我的情况下，原因是有一些图像在res文件夹名称包含一个大写字母..

只要用小写字母重新命名就可以了

2018-12-03 17:51:19

我也遇到了这个问题，我用这种方法解决了它。首先进入Gradle，点击clean。其次，单击Build。

确保不要从android studio清洁

2018-10-14 15:34:36

首先检查是否有任何错误在任何xml布局，如果然后解决它首先。

否则，从项目中删除junit依赖项并重新构建项目。

2017-03-28 08:19:12

尝试确保完整的包名在第一行。假设您有一个名为LoginActivity.java的文件和一个名为com.domainname.project的包。

java的第一行应该是