"cannot resolve symbol R" in Android Studio

729

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.

This question is tagged with android android-studio r.java-file

~ Asked on 2013-06-11 21:18:01

The Best Answer is


724

I had this this issue too. A simple 'gradlew clean' and 'gradlew build' did the trick.


Click on Build->Clean Project and that will perform a gradle clean

~ Answered on 2013-08-12 09:30:34


229

In the latest versions of Android Studio, at least for me, the following works:

"Tools" -> "Android" -> "Sync Project with Gradle Files"

In latest Android Studio 3.1.3 (July 2018), "Sync Project with Gradle Files" is available in main menu bar.

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~ Answered on 2013-11-19 09:51:51


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