Android Studio don't generate R.java for my import project
Goto File -> Settings -> Compiler now check use external build
then rebuild project
Best Solution for android studio Users :
Goto : Menu tab - > Build - > Rebuild Project
after rebuild Proj. your R.Java file problem will be solve automatically ..
I managed to regenerate R: File->Settings->Compiler
then UNCHECK "Use in-process build"
Rebuild Project