Book review: “Java by Comparison”

I need to start this blog entry with a full disclosure: One of the authors of the book I’m writing about contacted me and asked if I could write a review. So I bought the book and read it. Other than that, this review is independent of the book and its authors.

Let me start this review with two types of books that I identified over the years: The first are toilet books, denoting books that can be read in small chunks that only need a few minutes each time. This makes it possible to read one chapter at each sitting and still grasp the whole thing.

The second type of books are prequel books, meaning that I wished the book would have been published before I read another book, because it paves the road to its sequel perfectly.

Prequel books

An example for a typical prequel book is “Apprenticeship Patterns” that sets out to help the “aspiring software craftsman” to reach the “journeyman” stage faster. It is a perfect preparation for the classic “The Pragmatic Programmer”, even indicated by its subtitle “From Journeyman to Master”. But the Pragmatic Programmer was published in 1999, whereas the “Apprenticeship Patterns” book wasn’t available until a decade later in 2009.

If you plan to read both books in 2019 (or onwards), read them in the prequel -> sequel order for maximized effect.

Pragmatic books

The book “The Pragmatic Programmer” was not only a groundbreaking work that affected my personal career like no other book since, it also spawned the “Pragmatic Bookshelf”, a publisher that gives authors all over the world the possibility to create software development books that try to convey practical knowledge. In software development, rapid change is inevitable, so books about practical knowledge and specific technologies have a half-life time measured in months, not years or even decades. Nevertheless, the Pragmatic Bookshelf has published at least half a dozen books that I consider timeless classics, like the challenging “Seven Languages in Seven Weeks” by Bruce A. Tate.

A prequel to Refactoring

A more recent publication from the Pragmatic Bookshelf is “Java by Comparison” by Simon Harrer, Jörg Lenhard and Linus Dietz. When I first heard about the book (before the author contacted me), I was intrigued. I categorized it as a “toilet book” with lots of short, rather independent chapters (70 of them, in fact). It fits in this category, so if you search for a book suited for brief idle times like a short commute by tram or bus, put it on your list.

But when I read the book, it dawned on me that this is a perfect prequel book. Only that the sequel was published 20 years ago (yes, you’ve read this right). In 1999, the book “Refactoring” by Martin Fowler established an understanding of “better code” that holds true until today. There was never a second edition – well, until today! Last week, the second edition of “Refactoring” became available. It caters to a younger generation of developers and replaced all Java code with JavaScript.

But what if you are an aspiring Java developer today? Your first steps in the language will be as clumsy as mine were back in 1997. For me, the first “Refactoring” was perfectly timed, because I had eased out most of my quirks and got a kickstart “from journeyman to master” out of it. But what if you are still an apprentice in Java programming? Then you should read “Java by Comparison” as the prequel book to the original “Refactoring”.

The book works by showing you actual Java code and discussing the bad and ugly parts of it. Then it proposes a better solution in actual code – something many software development books omit as an easy exercise for the reader. You will see this pattern again and again: Java code with problems, a review of the code and a revised version of the same code. Each topic is condensed into two pages, making it a perfect 5-minute read (repeated 70 times).

If you read one chapter each morning on your commute to work and another one on your way back, you’ll be sped up from apprentice level to journeyman level in less than two months. And you can apply the knowledge from each chapter in your daily code right away. Imagine you spend your commute with a friendly mentor that shows you actual code (before and after) instead of only dropping wise man’s quotes that tell you what’s wrong but never show you a specific example of “right”.

All topics and chapters in the book are thorougly researched and carefully edited. You can feel that the authors explained each improvement over and over again to their students and you might notice the little hints for further reading. They start small and slow, but speed up and don’t shy away from harder and more complex topics later in the book. You’ll learn about tests, immutability, concurrency and naming (the best part of the book in my opinion) as well as using code and API comments to your advantage and how not to express conditional logic.

Overall, the book provides the solid groundworks for good code. I don’t necessarily agree with all tips and rules, but that is to be expected. It is a collection of guidelines and rules for beginners, and a very good one. Follow these guidelines until you know them by heart, they are the widely accepted common denominator of Java programming and rightfully so. You can reflect, adapt, improve and iterate based on your experience later on. But it is important to start that journey from the “green zone” and this book will show you this green zone in and out.

My younger self would have benefited greatly had this book been around in 1997. It covers the missing gap between your first steps and your first dance in code.

It’s a beginner’s world

According to Robert C. Martin, the number of software developers worldwide doubles every five years. So my advice for the 20+ million beginners in the next five years out there is to read this book right before “Refactoring”. And reading “Refactoring” at least once is a pleasure you owe to yourself.

Are programming books overrated?

In the last few weeks, we had an internship of a student that just finished academic high school (“Gymnasium”) and is looking forward to take up studies in computer science. He wanted to get in touch with the practical aspects of the career he is about to choose. The programming courses in school merely covered the basics of a programming language (Java) and some UML.

We prepared the student for the internship by feeding him several books we thought were appropriate for his level of knowledge. The books were a beginner’s book about Java (Head First Java), an introduction to unit testing (Pragmatic Unit Testing) and a foundation on clean code programming (Refactoring). Our student read them thoroughly and could make references to the chapters during pair programming sessions.

Retrospective on the books

But one feedback we got from him was that the books alone were nearly useless for his case. If there wouldn’t have been tutorial style pair programming coding sessions and several short lectures , he couldn’t grasp the deeper meaning of the book chapters he read (he suffered from the “blank slate blockade” several times). This came a bit as a surprise for us, as the student was very clever and really into it. It wasn’t the student, it was the books.

But you can’t blame it on “Refactoring”, for example, as this book is an all-time classic filled with really important knowledge. It has to be the medium itself, books are not the ideal source to learn about programming and software development.

Books are part of the academics

There is an old question in our profession. It revolves around if we are more like engineers or artists, craftsmen or scientists. In the core of this question is a uncertainty about the right model of education. Artists and craftsmen prefer more practical training, with apprentice/master relations and personal knowledge transfer. For engineers and scientists, literature and more standardized lectures are better suited. Academic knowledge is transferred during debate, not during exercises.

The duality of our profession

Projecting the feedback of our student onto this question, there seems to be a duality in our profession: Both (or all four if you want) approaches are needed to form a whole. You can’t learn the theory and expect to excel on the job. But pratical experience alone will not suffice to keep up with the pace of our profession. Good books are like afterburners here, you’ll be hurled forward by every page.


If it’s really true that we need to learn our profession both ways at once, pair programming (in the tour guide or backseat driver style) is an essential part of our qualification. And our current university curriculum fails to deliver this part. Students nowadays can team up to program together on an assignment, but that’s not learning from a master (unless one in the team has distinctly more experience than everybody else and is able to transfer it). So I vote to bring more craftsmanship to the academic education, as the books alone won’t cut it.

Your opinion?

What’s your opinion on this topic? Drop us a line about your thoughts.