Are you working with a project built on outdated technologies and legacy frameworks? It might feel like a ticking time bomb, but it doesn’t have to be. Through legacy code refactoring, you can breathe new life into old codebases, modernizing them without tearing everything down.
In this guide, you’ll learn what legacy code refactoring really means, why it matters, and how to do it effectively. We’ll show you techniques to evolve your code without breaking what already works.
Let’s start with the basics and build up from there.
What Is Code Refactoring?
Simply put, code refactoring is the process of restructuring existing code without changing its external behaviour. You dive into it, make some changes and then find yourself with a more sustainable code.
Alternatively, think of it like tidying up your office: your workspace stays the same, but everything is cleaner, more organised, and easier to understand and work with.
Code refactoring enables you to slightly transform older codebases, allowing them to adapt to newer software and technologies and perform better in general.
Why Does Legacy Code Refactoring Matter?
Let’s now explore why legacy code refactoring is essential. And why it’s a decent move to choose instead of switching to a whole new software or system architecture.
Simply put, when you opt for refactoring code, you get to:
Improve Code Readability and Maintainability
Legacy code is often written in a convoluted way, making it difficult to read and maintain. The restructuring you obtain when refactoring code allows you to understand it better, read it more easily, and add new features in the future more easily.
Reduce Technical Debt and Promote System Security
When executing code refactoring techniques, you clean the old and wrong stuff from legacy code (such as errors) and deliver a cleaner and lighter version of it to its users.
Likewise, this process enhances the system’s security by addressing and resolving various vulnerabilities, thereby shielding the software more effectively.
Prepare The System for Modern Tech Stacks or APIs
How adaptable is an outdated code to new frameworks, libraries or integrations? Not much.
Legacy code refactoring can remove all these obstacles from the old structure and align the codebase with modern standards, making it easier to implement new features or connect to up-to-date APIs.
Boost Performance and Developer Morale (No More Crying Over Spaghetti Code!)
As you can understand, having a cleaner, lighter and compatible code with modern tech stacks enhances the code’s performance by minimizing execution times and improving user experience.
But did you know that 51% of engineers have left or considered leaving their jobs due to technical debt? While your company suffers tangible losses due to gibberish outdated code, your employees are paying the emotional tax of having to fix ever-emerging issues instead of working on new creative solutions and growing in their profession.
When you don’t have to waste hours untangling confusing logic, you are happier to work with it and have more energy to focus on innovation and peak results.
Code Refactoring Techniques That Work
So, now that you know what legacy code refactoring is and its benefits, let’s go through some reliable techniques you can practice when dealing with legacy systems and code-related matters.
These techniques may refer to the preparation phase, the real-time refactoring phase, and the post-restructuring phase.
Characterization Testing (Preparation Stage)
Before making any changes and starting the process, run tests to understand how the system behaves. This will give you a safety net and a clear picture of what you must deal with.
Small Changes Method (Refactoring Stage)
Break large blocks of code into smaller, reusable pieces to isolate functionality and reduce complexity. This will benefit your code refactoring process in two ways:
Help you better grasp the function and behavior of the legacy code (which may be a mystery after all, especially if the original developers are no longer part of the team)
Ensure you proceed with safety (fewer chances to insert a bug and more chances to find and eliminate it if inserted)
Isolate dependencies (code parts that connect with external systems or third-party libraries, for instance) and manage them more efficiently
Discover how legacy systems are holding insurers back and how to move forward.
Choosing High-Impact Areas (Refactoring Stage)
Meaning the ones that are more critical and gain the primary focus of the whole legacy code. By prioritizing these areas, you begin refactoring the code from the points that are more meaningful and impactful.
Encapsulate Field / Variable (Refactoring State)
With this technique, you protect internal states with getter/setter patterns or updated access control. By not letting other parts of the code directly change a variable, you reduce unintended side effects and make the code more robust.
Rename for Clarity (Optional yet Helpful)
Meaningful names make a huge difference. Rename functions and variables to reflect their purpose and make the legacy code easy to read, understand and in the end work with.
Evaluating and Monitoring (Post-Refactoring Phase)
After doing your legacy code refactoring, it is time to:
Evaluate that it is still functional and continues to work as you wish
Monitor its performance and other important metrics (such as memory usage or response times).
Gather end-user opinions to determine the refactoring process’s impact and identify areas for improvement.
Tools Used for Refactoring
| Tool | Best For | Platform | Key Features |
| ReSharper | .NET legacy code | Visual Studio | Refactoring, code analysis, suggestions, navigation |
| NDepend | Advanced .NET analysis | Windows | Static analysis, dependency graphs, tech debt rating |
| IntelliJ IDEA | Java and Kotlin | Cross-platform | Smart refactoring, inspections, and test integration |
| SonarQube | Multi-language support | Server-based | Code smell detection, maintainability tracking |
| VS Code | Lightweight refactoring | Cross-platform | Extensions, search and replace, rename symbols |
| Eclipse | Java legacy systems | Cross-platform | Refactoring wizard, method extraction, and rename tools |
Apart from the above helpful techniques, there are also several tools to assist you with refactoring code safely and efficiently.
Here is a list of the most popular of them:
ReSharper – Ideal for .NET projects and .NET developers that can benefit from its advanced code analysis and navigation features.
Visual Studio Code Refactoring tools – Lightweight yet flexible. They offer extensions that help you extract methods and clean up code across projects.
IntelliJ IDEA – Ideal for Java and Kotlin projects. It comes with smart refactoring, code inspections, and tight integration with testing tools.
Eclipse for Java – With its built-in refactoring wizards, you can eclipse the old stuff safely and consistently.
SonarQube – This tool works with multiple programming languages to detect code smells, track maintainability, and enforce quality rules.
NDepend – Finally, NDepend is a powerful .NET static analysis tool that highlights dependencies and tracks technical debt, ideally for big-picture code improvements.
Best Practices for Code Refactoring Legacy Applications
Here are the best practices for refactoring legacy code:
Ensure you test things: Adding tests from the very beginning will help you avoid breaking anything.
Refactor in small chunks: Take it one module at a time. Divide the refactor code project into sections and work on them gradually.
Use version control: Always. So you can roll back if things go wrong. Imagine not having that ability.
Communicate with your team: Refactoring isn’t a one-person orchestra task – keep your team in the loop. Consider using Agile practices.
Document everything: Take detailed notes of the process, including your reasons for refactoring and the outcome.
Ready For Some Legacy Code Refactoring?
Dealing with legacy code doesn’t have to be a nightmare. With the right approach and the proper tools, you can modernise it piece by piece while keeping the operations smooth and running.
However, if you want complete peace of mind and the best results, you can trust our experienced team to transform your legacy system for you.
Book a call now and get the best code refactoring services tailored to your needs and at the most competitive prices in the market.
FAQs
1. What Is Code Refactoring, and Why Does It Matter?
To refactor code means to take all the necessary steps to improve the internal structure of existing code without altering its behaviour. It’s a process that makes code easier to read and allows you to maintain and even extend it. Given these benefits, you can understand why code refactoring matters in the programming world.
2. Is It Risky to Refactor Legacy Code?
It can be, yes. It all depends on your knowledge and taking all the necessary precautions. For instance, if you don’t run any tests before the legacy code refactoring process, you risk missing essential data about the code’s performance. On the other hand, if you execute characterisation tests, go for small changes, and check version control, you can refactor safely.
3. Which Tools Are Best for Code Refactoring In .NET?
Some top tools include ReSharper, NDepend, and Visual Studio’s built-in refactoring features. Each of them has its benefits, so ensure you’re using the right one for your code refactoring process.
4. How Do I Start Refactoring a Legacy Application?
Easily! Start by writing tests to understand the code’s current behavior. Otherwise, you’ll go in all blindfolded. After running those tests and getting a clearer picture of what you’re dealing with, start refactoring in small, safe increments. As easy as pie!
