This book gives an overview and discusses in-depth knowledge for the analysis and improvement of your software code. You will be able to apply principles, patterns, techniques, and tools needed to write clean code. Nothing affects the work of a team as much as bad, illegible, sloppy, and quickly written code that has not been designed carefully. Team dynamics can be improved, requirements can be redefined, and the schedule can be modified. However, if bad code takes over, it becomes more and more a burden for the team. Programmers should develop all the time. Even if they think that they have sufficient skills and knowledge to move around in current projects, they should not stop there, and it is worthwhile for them to learn new concepts, approaches, language, and frameworks from time to time. Learning should be a journey and not a destination. This book discusses the basics of software quality, principles, patterns, and best practices of writing better code. It also contains many code examples in Java of increasing complexity. Among other things topics like software metrics, static software testing, and tools which can help to measure software quality will be covered. Software testing is not limited to a specific phase of a project. Already during the coding phase or the build process, critical and difficult to find software defects can be detected in the source code. The necessary procedures and tools are presented in this book.