This week's book giveaway is in the OCAJP forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide 1Z0-808 and have Jeanne Boyarsky & Scott Selikoff on-line! See this thread for details.
"R.java" is auto-built by Eclipse if it can successfully do a build of a Project;
1. are you sure there are no other compilation problems in your project?
2. are there any problems listed under "Problems" view?
3. are your project properties properly set?