I was having a problem with all my R.string|id references not being recognized in QuizActivity.java, but they were in the R.string section of the gen file. Quite frustrating when everything is exactly like in the book.
Problem was resolved when I noticed a warning for R.android which had been imported as a result of shft-cntl-O issue suggestion. Removed it and presto everything is fine.
Using ADT Build: v22.3.0-887826.