How do I fix “unknown entity 'R' ”?

Question

I am using AIDE on my Nexus 7 and suddenly I am unable to build / run my App. I get 18 errors of this kind and yes I've already tried turning it off and on again.

Answer 1

Check your namespaces (package name) and also folder structure.

I had this error when I change namespace of *.java files, and forget make namespace change also in build.gradle file of project (android - defaultConfig - applicationId). AIDE then try to import non-existent R, and shows the error, because generated resources are in another namespace (package).

Another option is to go to main menu in AIDE then "more..." - "code" - "organize imports" and see what choices you have to choose for importing R.

Answer 2

删除自动生成的 build/ 文件夹和 build.gradle 文件，我能够再次构建但不能安装（没有详细信息），不得不重新创建一个新的应用程序项目和回拷源和资源。

Answer 3

当您更改包名称并忘记更新应用程序的build.gradle文件中的applicationId时，就会发生这种情况。

Answer 4

Goto your project (In File Browser) and delete the build folder and do a rebuild. I had the same problem and is fixed