After updating Android Studio 0.1.6 it sometimes can’t find R and you have to rebuild your project.
java /*.java : cannot find symbol location : class com.*.R
A workaround: Module project settings -> Dependencies -> move one of the item up or down -> OK, it’ll regenerate the R.java
Another temporary wordaround: Turning off Preferences -> Compiler -> Use External Build
Google is aware of the problem, the bug report is here: https://code.google.com/p/android/issues/detail?id=56843