Refactoring Java Code: A Practical Guide

The book "Refactoring Java Code" is a practical guide to transforming tangled, unreadable, or outdated Java code into a clean, maintainable, and extensible system. The author thoroughly examines real-world examples from industrial development, showing how to identify "code smells" and safely eliminate them.

What is this book about?

• Core refactoring techniques: extract method, move field, replace conditionals with polymorphism, and others.
• Working with legacy code: how to test and modify code without tests, dependency extraction.
• Anti-patterns in Java: god object, long method, message chain, and ways to eliminate them.
• Refactoring using modern tools: IntelliJ IDEA, SonarQube, JUnit 5.
• Design on the fly: how refactoring relates to SOLID, KISS, DRY, and YAGNI.

Who is this book for?

• Java developers of all levels — from juniors to seniors. Juniors will learn to write clean code from the start, experienced developers will systematize their knowledge and learn new techniques.
• Team leads and architects — will find strategies for implementing a refactoring culture within the team.
• Technical leads — will get ready-made templates for code reviews and technical debt assessment.

What will you learn after reading?

• How to safely refactor code without the risk of breaking functionality.
• How to use automatic refactorings in the IDE.
• How to write tests for existing code before modifying it.
• How to deal with technical debt in large projects.
• How to transform spaghetti code into a modular architecture.

The book contains over 50 exercises with step-by-step solutions and ready-made examples on GitHub. Each chapter ends with a self-check checklist.

This is not just theory — it is a tool you can apply to your project today. Suitable for Java 8–21, Spring, Hibernate, as well as plain Java SE.