The R file is a resource file that is generated as part of the build, a prerequisite to the build of your java files.
On my system, the R file went missing. I searched and I searched and no one gave me help. The excellent StackOverflow site did give me a hint, though, to look at the problems view. And that is where I found the issue …
I am using 64 bit Eclipse and Android tools, and some of the libraries are only available in 32 bits, so you have to ensure that you install them. Good to know.
I tried to post this back to Stack Overflow, but I don’t have the required 10 “reputation” points 
