Java Generics and Collections by Maurice Naftalin & Philip Wadler (O’Reilly)
This is a very good book for learning Java Generics and Collections. It has many commonly used Generic samples and does give you a very detailed and comprehensive explanation to each sample. The chapters are well organized.
The Collection parts are also good (but not great – I would like to see more commonly used collection types). It tells you how to use each correctly. There are a lot of in-depth explanations. I’d highly recommend this book.