Practical Design Patterns for Java Developers: Hone your software design skills by implementing popular design patterns in Java

It is remarkable book with clear explanations of design patterns and many useful examples including references to JDK.One of the standout features is chapter about concurrency design patterns, which helps to understand Java concurrency functionality better.I also appreciated the author's attention to best practices and common anti-patterns.Overall it is easy to read, cohesive guide to design patterns from the latest Java version prospective.

Early in my career, I read “Design Patterns: Elements of Reusable Object-Oriented Software.” This book is often known as GoF (Gang of Four) after the four authors: Gamma, Helm, Johnson, and Vlissides). This was an excellent book and I referenced it heavily. The patterns are still useful to this day. This book was published in 1994. (Soon we can wish it a happy 30th birthday!). In a fun coincidence, GoF is about the same age as Java.“Practical Design patterns for Java Developers” breaks up the design patterns into the same groups – creational, structural, and behavioral. It adds examples of the features from the JDK itself which is great for linking it to things many Java developers have experienced.It also adds examples of implementing the pattern using modern Java. (Java 17 which was the most recent long term release at the time of the book's presenting.) These new features are used heavily making the book good examples of how to use the language.Given that almost 30 years have past, there are more key patterns now. This book covers all the GoF creational patterns and adds object pool, lazy initialization, and dependency injection. For structural, the book adds the filter, front-controller, marker, module, and twin patterns. For behavioral, the book adds the caching, null object and pipeline patterns.The book also covers concurrency patterns and anti-patterns which weren't in GoF. And all that is parts 2 and 3 of the book. Part 1 of the book, gets everyone on the same page. It covers the OOP (object oriented programming), APIE (abstraction, polymorphism, inheritance, and encapsulation) and SOLID (Single responsibility, open-closed, liskov substitution, interface segregation and dependency inversion) terminology in addition to how the JDK is structured.All chapters except anti patterns end with review questions (and an appendix with answers) to solidify the information. In addition to the patterns material, I particularly liked the memory graphs in the anti pattern chapter. If you bought a printed book, you get a PDF and color diagrams free. (I didn't try this as a got a review copy). The code is also available on GitHub including the commands to run each example.You do need to be comfortable reading Java to make sense of this book. If you aren't there yet, grab another book first and come back to this one. If you are comfortable reading Java, this book is for you!I received a complementary copy from the publisher in exchange for writing this review.

I took a design patterns class in college years ago and I was looking for an updated book to refresh myself, this was exactly what I was looking for.

Miroslav Wengner, the author of this book, has been an active member of the Java community since he worked at Sun Microsystems, back in another age. He has frequently contributed his knowledge, and has impressively had a prolific output of useful material and articles throughout his career since then.I should disclose here already, that I know Miro well, and he is a fellow Java Champion, so this may not be a completely unbiased review. But I still stand beside my positive feedback here. If in doubt - do verify what I say about this book yourself, or check with someone who has the equivalent level of knowledge. Personally, I feel that my observation that Miro's writing, while coming from deeply technical level, should be accessable to almost everyone with a little bit of experience in Java programming and object oriented paradigms.The book is not the first of its kind in the Java space, but it's probably the first that I have seen with the specific details provided as elegantly as way Miro does it. Miro doesn't just talk about design patterns and best practices, and what has happened to the Java platform through its history. I can also tell from the way he has written the book, that the design patterns he has chosen to write about are based on his impressive vertical knowledge too, from Java applications, and all the way down to the bare metal.Another observation that I have made over the years in various tech leadership positions over Java technology stacks, is that many senior Java developers with great domain knowledge of all the complex dependencies and libraries involved building modern software, still has untapped potential if he or she doesn't understand how the runtime(in this case the JVM and OS) executes their code, and how the CPU actually works (concepts like page faults, cache misses, memory bandwidth, and so on). This does not mean that a good Java programmer needs to explicitly do things that break the abstraction layers towards the native part of the platform - or usually hack about with these kinds of details. That is also very much not something that isn't recommended. There are typically several "nice" ways to get performance and scalability. But understanding at some coarse grained level of detail how the black box that is the JVM will execute your code, will still turn you into a massively better high level programmer. This, without you having the knowledge to build your own JVM and step your way through the garbage collection process with a debugger, or anything of that sort. I strongly believe this is a valid observation.What makes Miro's book stick out when it comes to this, is that I can tell that he has chosen to elaborate on design patterns that are best-practice on the high level side, but also tend to translate well into efficient code running on the JVM. The author is not necessarily explicit about this, in fact, I believe he has deliberately chosen not to be. But I can still infer much from his various pedagogic explanations. This is great, IMHO. I think it is very hard to promote certain practices that a person with good vertical knowledge has, when it comes to diving into complicated explanations of exactly what is going on under the hood for every use case. Adding lots of detail here, wouldn’t necessarily do any harm to the reader. In some cases, like the great "Optimizing Java" by Evans, Newland et al, this is the actual message the book tries to convey. In this case, though, I believe it would have significiantly reduced Miro's audience and the amount of good this book will do, where he do go into implemenation detais. However, the way he picked the design patterns to go over, and the way he explains them, are a great source of nderstanding for engineers who want to improve themselves and that strive to reach the lead software architect level. And this is the right end to start - not prying apart a lot of black boxes to look in side, but rather evangelize on best practice ways to do something in a high level language like Java, that will also bring the benefit of more efficient and less resource hungry programs.The book is made out of several main sections, first a summary of design patterns (general) and a bit about the Java platform and its functionality. The main part of the book follows next, which shows how design patterns should ideally be implemented in Java, and the relevant portions of the JDK libraries that should be used. The final part of the book talks about other essential patterns and anti-patterns. The anti-patterns are the most interesting topic here, IMHO, because typically they are not described in any detail in most literature.The book talks about how certain anti-patterns are bad design, create technical debt and so on, but also has good examples of how seemingly clean code will, in reality, stretch the intended JVM limits, and without the user understanding it, put unnecessary performancedegradations or scalability limits in the system. I really wish there were more of these kind of articles, because this ties directly into my observation that if you do know the vertical of the platform, without actually breaking any abstraction layers or anything. You should still be aware of things like autoboxing overhead in Java, and that the JVM can't magically detect and deduplicate equal Strings on the heap, without extra analysis overhead (typically deduplication as a function of GC) and so on. I think that a great topic for an expansion on this book would be good patterns and anti-patterns when it comes to interference in the JVM. There are not only things to be avoided that a good high level programmer should know, there are also things that are done as premature optimizations but do not alwaysmatter for performance. This section serves as a really good starting point to continue learning about how the Java program interacts with the platform, and should be a good primer for any developer who, before reading Miro's book, may have felt slightly nervous about delving into something heavier, more specialized on-the-JVM behavior, and more low level - e.g. the excellent "Optimizing Java" by Evans, et al.Finally - to summarize - Miro's book is fairly short, consise and to the point. And still it manages to present and explain common best practices used by pretty much any senior engineer in the Java ecosystem to anyone. I think this is quite valuable. It might evenhade been easier to write a thick detailed book, going depth first all the way down to the silicon, describing every detail of what makes a design pattern effective (and not just good abstraction).The way the book balances the width and depth of the material, and that it has still obviously been carefully written to promote patterns that are healthy both for general high level programming, but also gives you efficient implementations when they are running on the JVM, OS aand Silicon, is well thought through. The author also stays far away from the other common failure of a short technical book, which is not really expanding the reader's knowledge much, or even worse, just makes various "dangerous" buzzwords stick in the reader's mind ("blockchain" anymone?)I definitely recommend this book to anyone who wants to be a better Java architect, or for any Java architect already there, who wants to validate (and possibly expand) his or her knowledge. I am impressed by the outline, the material chosen, and the order and the way it is presented. This is really well done!

Developers need to master multiple skills to become successful. If you plan to work as part of a team, one of those skills will be design patterns. Patterns give us a concise way to express complex concepts that recur frequently in software development. For example, if you say that this part of the design will require a singleton, your team members will immediately understand that you only want a single instance of an object (and the complexities of guaranteeing that, especially in a multi-threaded application).The definitive book on patterns, written by the so-called Gang of Four, has been around for nearly thirty years. However, this is written in an abstract form without demonstrating the patterns used with a specific programming language.Miroslav Wenger’s book has taken a comprehensive approach to patterns targeted at the millions of developers using Java as their language of choice. Thirty-four core patterns are divided into creational, structural and behavioural. For each, a clear description and the motivation for use and sample Java code are provided. The book's second half looks at a further eight patterns targeted at concurrent applications and an equally important discussion of anti-patterns or things to avoid.If you’re a Java programmer looking to understand how patterns can be applied to your code, this book is for you.