This is a book about design that I have been working on years, basically ever since I first started trying to read Design Patterns (Gamma, Helm, Johnson & Vlissides, Addison-Wesley, 1995), commonly referred to as the Gang of Four1 or just GoF). There is a chapter on design patterns in the first edition of Thinking in
C++, which has evolved in Volume 2 of the second edition of Thinking in C++, and you’ll also find a chapter on patterns in the first edition of Thinking in Java (I took it out of the second edition because that book
was getting too big, and also because I had decided to write this book). This is not an introductory book. I am assuming that you have worked your way through Thinking in Java or an equivalent text before coming
to this book. In addition, I assume you have more than just a grasp of the syntax of Java. You should have a good understanding of objects and what they’re about, including polymorphism. Again, these are topics covered in Thinking in Java. On the other hand, by going through this book you’re going to learn a lot
about object-oriented programming by seeing objects used in many different situations. If your knowledge of objects is rudimentary, it will get much stronger in the process of understanding the designs in this book.