Android developmentFswitch...case with R.id.xx in Intellij

Android developmentFswitch...case with R.id.xx in Intellij

There is an old big project developing in eclipse.I import it into
Intellij 12.1.4
Because Intellij idea doesn't generate a R.java file as eclipse.I can't use
switch...case:R.id.x
So,the project build failed.
IntelliJ Idea not generate id in R.java
How can i do with it?
Thx.