Head First Design Patterns: A Brain-Friendly Guide

Head First Design Patterns is an excellent introductory text for design patterns, plus object oriented design in general. Each chapter in the main part of the book covers one or two of the most common design patterns in great depth, including motivation, sample code, exercises, as well as answering many of the questions a reader is likely to have. Additionally, one of the things that makes the book great is that each chapter uses the context of the design pattern to introduce one or two important object oriented design principles such as the Open-Closed Principle and the Principle of Least Knowledge. Less common patterns are covered in the appendix, although in much less depth. I bought this book for my 17-year-old nephew -- who is in the second year of a high school computer programming course -- as a companion to the Gang of Four book. I think the two books work well together, with Head First Design Patterns working as a more accessible introduction to design patterns, and the Gang of Four book serving as a reference for later on. He definitely finds the Head First book easier to read as a beginner. Even I, with a college degree in Computer Science and 20 years in the software development industry, find it valuable, at least as a review. For those wondering about which edition they will get, I bought this book through Amazon and received the tenth anniversary edition, updated for Java 8. The main difference is that it takes advantage of the newly-introduced Lambda Expressions. Although the book uses Java throughout, C# developers will have little if any trouble with the examples. In many cases, the code is identical. Slight nitpick: Some of the patterns in the appendix are given short shrift in the interest of space. For example, the section on the Visitor Pattern leaves out the important fact that one of the main motivations for the pattern is to overcome the limitations of languages that support only single dispatch. Said another way, the Visitor Pattern is trivial to implement in languages that support multiple dispatch. For more detail on these design patterns, I recommend the Gang of Four book, or online resources.

This book aims to teach us how to reuse design patterns that have been used over and over again. While this book does not cover all patterns in detail, it covers the patterns that are commonly used according to the authors' mind. In overall, this is the book you want to buy as a starting point to learn design patterns. To begin with, before reading this book, you have to know about Java programming language along with the object-oriented features such as encapsulation, inheritance, and polymorphism. Bear in mind that by having solid object-oriented knowledge does not make you a good object-oriented designer. I thought the opposite until I read this book. For those who do not know the language and/or the object oriented feature, they should study them first before attempting to read this book. When reading this book, please note that the primary intention of this book is to teach you about design patterns. Therefore, if you find the examples are not what you expected (too simple, childish, imaginary, and so on), you need to know that the examples are made as simple as possible so you can concentrate on learning design patterns. Unfortunately, some people just do not understand this approach. They probably want examples that have hundreds line of code to explain each patterns and I am very sure if this was the case, they would give bad review anyway by arguing that the examples are too complex. The only negative thing is the fact that not all 23 patterns are covered. I wish all of them were covered in a single book and even if the price were twice as much I would certainly buy it. I do not know why the authors did so. They covered only around 13 and cramp the others in 20 pages in the appendix. In my personal experience, after reading this book, it changed my paradigm toward object-oriented design and made me ask myself, "Why I didn't buy this book earlier?" Had I bought it earlier, my campus projects would have gone easier. In addition, ever since I read this book, I often think about the pattern(s) that can be applied in the other programming books' code example, especially when the examples have too many if and if else statements as they could be refactored using state pattern or command pattern. The reason some programming books do not bother with design patterns (even though the authors probably know about it) is because not their focus in their books. That is why this book is useful. Also, please be aware that in this book source code, the instance variables are not declared private. In reality you have to make it private according to the principle of the least privilege. Finally, I highly recommend this book to anyone who already knows Java and its object-oriented features as it helps you to learn commonly used patterns and to design better using best design principles (open closed principle, encapsulate what varies, etc).

Da ich mich hauptsächlich mit Embedded-Entwicklung in prozeduralen Sprachen befasse, war mir das Thema Design-Patterns bisher relativ unbekannt. Im Web findet man einiges zu diesem Thema, allerdings meist sehr trocken und in Form von Pattern-Katalogen ohne konkreten Praxisbezug. Meist wird lediglich ein Beispiel in diversen Programmiersprachen umgesetzt und fertig. Über die Hintergründe, die zur Entwicklung eines Patterns geführt haben, findet man meist eher wenig Informationen. Nach einigem Stöbern bei Amazon fand ich dieses Buch, und ich muss sagen, dass sich die Anschaffung voll und ganz gelohnt hat. Keine sture Auflistung möglichst vieler Patterns, stattdessen eine didaktisch eigenwillig, aber äußerst effektiv gestaltete Reise in die fiktive Stadt Objectville, deren Bewohner mit allzu bekannten Problemen bei der Software-Entwicklung zu kämpfen haben. Jedes Kapitel widmet sich einem Pattern, wobei eine sinnvolle Auswahl aus den GoF-Patterns getroffen wurde. Beginnend mit einer Problemstellung werden die Patterns Schritt für Schritt erarbeitet, wobei auch Irrwege gezeigt und erläutert werden. Zwischendurch sorgen kleine Aufgaben für eine Festigung des Gelernten. Der Schreibstil ist locker, das Layout gezielt ungewöhnlich, um das Gehirn zur Mitarbeit anzuregen statt mit ewigen Textmengen zu langweilen. Für mich geht dieses Konzept auf, man kann das Buch regelrecht verschlingen, und trotzdem bleibt der Stoff "hängen". Zweiflern empfehle ich "Pragmatisches Denken und Lernen" von Andy Hunt, das einige Einblicke in die Hintergründe solcher Lehrmethoden bringt. Gute Englischkenntnisse sollten natürlich vorhanden sein, was allerdings bei der angesprochenen Zielgruppe heutzutage wohl ohnehin unerlässlich sein dürfte. Nachtrag: Meine Java-Kenntnisse würde ich maximal als "grundlegend" bezeichnen. Trotzdem hatte ich keine Probleme mit dem Verständnis der erarbeiteten Code-Beispiele, da es in diesem Buch nicht um das Ausreizen aller Sprachfeinheiten von Java geht, sondern eben um Software-Design und Struktur.

Es un libro que todo desarrollador debería leer, vale mucho y es una joya. Son claros y concisos al momento de explicar los temas además siempre mencionan las variantes de los patrones y en muchos casos muestran como lo hace Java y si existe alguna falta en la manera en que java ha implementado ciertos patrones de diseño.

とてもしっかりしてる良本

Excelente livro, boa didática e já utiliza o Java 8

Great book for beginners. It explains the concepts in a fun, interesting and interactive manner. Would recommy this book to anyone willing to learn design patterns