转自stackoverflow
https://stackoverflow.com/questions/17054000/cannot-resolve-symbol-r-android-studio
I had this this issue too. A simple ‘gradlew clean‘ and ‘gradlew build‘ did the trick.
实际解决，就是android studio中右键选中工程，然后点击make module。
cannot resolve symbol r android studio
原文：http://www.cnblogs.com/putinlu/p/4185263.html