In a day when programs are asynchronous and responsiveness is paramount, reactive programming can help you write code that is more reliable, better scalable, and runs faster. Thanks to this book, a Java programmer will learn about the reactive approach to problems and learn how to create programs that incorporate the best features of this new and very promising paradigm. This book contains an in-depth and detailed presentation of the concepts and principles of using reactive programming in general and RxJava in particular. The book can be used both for sequential study of the subject and as a library reference.