“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

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

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

我也有这个问题。简单的“gradlew clean”和“gradlew build”就成功了。

点击Build->Clean Project，将执行gradle Clean

2013-08-12 09:30:34

在一个非基础特性的即时应用活动中，你可以调用R.id.fromFeatureOne和R.is.fromFeatureTwo。因此，来自不同资源的项目被引用为单一资源来源。

两者都将被高亮显示为可接受的，您甚至可以跳转到源代码。但是构建会导致一个错误:“不能找到符号R.id”，这是相当棘手的原因，因为什么都没有突出显示。

解决方案是调用com.example.feature.one.R.is.fromFeatureOne和com.example.feature.two.R.is.fromFeatureTwo。

在谷歌:https://issuetracker.google.com/u/0/issues/77537714也发布了一个bug

2018-04-04 09:37:45

在我的例子中，导入应用程序域名后跟“。R解决了这个问题。例子: