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Is cluttered code slowing you down? Do you wish to alter and clean up the code? Code refactoring can come to your rescue. It cleans up your code, besides helping to boost its performance, maintainability, and readability. Code refactoring could help refine, optimize, and future-proof your code like a pro and reduce any technical debt.

Generative AI coding support can help software engineers refactor code 20 to 30% faster – McKinsey

If you are on the fence about code refactoring, we’ll walk you through its intricate details. Plus, we’ll dive into practical examples, introduce you to helpful tools, and share best practices to turn your code into a well-oiled machine. Let’s get started!

Code Refactoring

What is code refactoring? With example

Code refactoring is the process of restructuring to improve the existing code without changing its external behavior. The goal is to cleanse the internal structure of the code, making it more readable, maintainable, and efficient, while preserving its inherent functionality. It tidies up the codebase—making it more organized and easier to maintain. As per Deloitte, it can help modernize legacy applications without altering functionality. Python e.g.,

Original Refactored
def factorial(n):
if n == 0:
return 1
else:
return n * factorial(n – 1)		 def factorial(n):
result = 1
for i in range(1, n + 1):
result *= i
return result

The refactored simple loop version removes the unnecessary “else” block, avoids a potential stack overflow, and provides a clearer understanding of the logic without losing the functionality of calculating the factorial.

Why should you refactor your code?

  • Improves code clarity, making it easier to understand and navigate the codebase.
  • Less convoluted code, facilitates easier maintenance and updates.
  • Enables easier adaptation while scaling to adjust to the evolving requirements.
  • Modularize code, making code components more reusable, testable, and adaptable.
  • Detects and eliminates bottlenecks and bugs for crystal-clear code and efficiency.
  • Enforces coding standards and consistency across the codebase.
  • Improves collaboration, reduces communication overhead, and streamlines software development.

What is the difference between code optimization and code refactoring?

Code Optimization

  • Improves resource efficiency, execution time, and performance of the code.
  • Focuses on improving the memory or processing time.
  • May change the original code to achieve performance gains.
  • Involves changes to algorithmic or low-level implementation details.
  • May sacrifice code readability to achieve performance targets.

Code Refactoring

  • Aims to improve the structure, readability, and maintainability of the code.
  • Looks to enhance code organization without altering external behavior.
  • Retains intrinsic functionality while enhancing the code quality.
  • Involves holistic restructuring, simplifying, and clarifying code.
  • Usually, doesn’t consider performance improvements as the main goal.

What are the 6 Code Refactoring Techniques?

1. Composing Methods:

Break down complex methods into smaller, more manageable ones. Extract a portion of the code into a new method, inline a method, and replace the method with a method object. Further, split multi-purpose variables into distinct variables, introduce explanatory variables, replace “temp” with “Query”, and don’t pass multiple parameters to a method.

2. Moving Features between Objects:

Developers focus on transferring methods or fields from one class to another to improve the structure of the code, reduce coupling, enhance clarity, and create classes that align better with their needs. You can move methods & fields, extract classes, and move constructors for a more cohesive codebase. A field e.g., in Java.

Original Refactored
class SourceClass {
int movedField;
}class TargetClass {
// … other fieldsint movedField;
}		 class SourceClass {
// … other fields
}class TargetClass {
int movedField;
}

3. Refactoring by Abstraction:

Condense the shared features of several classes into an abstract class. Because it defines a common interface for similar classes. The abstraction promotes reusability and simplifies coding. Maintainability, adaptability, and code readability improve by centralizing common functionality and minimizing code duplication through a shared abstract class.

4. Simplifying Conditional Expressions:

To lessen the cognitive effort, reorganize intricate and nested conditions to make them simpler. It is simpler to isolate and test well-defined conditions separately when this is done. E.g., Reduce complex nested conditions to a single statement or use logical operators to merge them.

5. The Red-Green-Refactor:

An iterative cycle in Test-Driven Development (TDD) encouraging continual tests for clean and well-tested code. It involves:

Red: Write a failing test for the desired functionality with a clear goal
Green: Make small changes to pass the test, prioritizing functionality
Refactor: With the test passing, improve the structure, readability, and maintainability

6. Simplifying Method Calls:

Make method interaction clearer and more efficient. Do this by adding parameters, removing unused parameters, renaming methods, separating query from modifier, creating helper methods, and avoiding multiple similar methods to result in methods with well-defined purposes. Given below is a field e.g., in Java:

 

Original Refactored
public void processOrder (String customerName,
String productCode, int quantity, boolean isPriority)
{ // method implementation }		 public void processOrder(Order order)
{ // method implementation using order object }

 

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Top 3 best practices to follow while Code Refactoring

1. Small incremental changes:

Break down the process into bite-sized modifications. Reduce the likelihood of errors disrupting the existing functionality, ensuring the code stays sleek without any faux pas. It’s just like trying on an outfit, we make a change, check the fit, and if it isn’t there, tweak it till it “fits like a glove.“ Stick to systematic adjustments, minimize significant risks, test continuously, and stay agile.

2. Embrace Automation:

The labor-heavy and bloated repetitive practices with oversights leave efficiency and quality in the backdrop. Automation, as your coding sidekick, expedites the process. Bots remove the manual sweat of the refactoring workflow to sniff out efficiencies, redundancies, and errors to tidy up the code lines. Ensure speedy scans, remove duplicates, and more at the drop of a hat.

Deloitte, using its automated tool InnoWake was able to refactor 1.2 million lines of
COBOL code and 1,400 objects – Deloitte

3. Eliminate Code Duplication:

Consolidate redundant code throughout the codebase. Stick to the “Don’t Repeat Yourself (DRY)” tenet focusing on a single, unambiguous purpose within the code block. Remove the replicated code and turn it into a new procedure. Work towards a referenceable, cohesive, and modular code. Use variables, use functions to summarize, and avoid copy-paste.

Top 7 Code Refactoring Tools to Use in 2025

1. Refact.ai

Refact.ai is an AI-powered refactoring assistant that plugs directly into IDEs like VS Code and JetBrains. It uses large language models to understand your code’s intent, suggest improvements, simplify logic, and restructure functions for readability and performance. It supports multiple languages and integrates smoothly into modern CI/CD pipelines.

2. JetBrains IntelliJ IDEA (with AI Assistant)

IntelliJ IDEA remains a powerhouse for Java and Kotlin refactoring, and in 2025, its AI Assistant feature adds intelligent code insight. It automates method extraction, variable renaming, class decomposition, and more with minimal human input. It also flags architectural smells early, helping teams avoid long-term technical debt.

3. Visual Studio Code (with GitHub Copilot & Extensions)

VS Code combined with GitHub Copilot and AI refactoring extensions now provides real-time suggestions to restructure messy code, optimize loops, and remove redundancies. While not a dedicated refactoring tool, its ecosystem allows deep customization and AI-powered assistance across dozens of languages, from Python to C#.

4. CodiumAI

CodiumAI focuses on refactoring code through the lens of test-driven improvement. It suggests safe refactors by validating logic through autogenerated unit tests. Particularly useful for legacy systems, CodiumAI ensures your refactoring doesn’t break production logic—making it a favorite for enterprise teams modernizing older codebases.

5. Sourcegraph Cody

Sourcegraph Cody provides powerful AI-assisted code navigation and refactoring at scale for large monorepos. It understands cross-repository dependencies and offers inline suggestions to split large files, modularize functions, and refactor with context awareness. Great for engineering teams working with large-scale enterprise apps.

6. Resharper (by JetBrains)

A veteran in the .NET ecosystem, ReSharper continues to dominate in 2025 with enhanced AI-driven suggestions and deep refactor automation. It excels in real-time code quality checks, method extraction, renaming, and converting legacy patterns into modern C# syntax. It’s tightly integrated with Visual Studio for seamless developer experience.

7. Embold

Embold focuses on preventive refactoring by identifying anti-patterns, code smells, and complexity hotspots before they snowball. It provides a visual scorecard of code health and suggests automated fixes. With support for multiple languages and Git integrations, it’s ideal for code reviewers and teams seeking cleaner, more maintainable codebases.

How to measure the effectiveness of code refactoring?

  • Check the number of open codebase issues and aim for zero
  • Check the number of TODO or FIXME comments across your codebase
  • Track the number of bug reports in the refactored code
  • Count the number of failed unit tests, ideally want to be zero
  • Check for code coverage and aim for a higher code coverage
  • Track the amount of reduction observed in duplicated code

Wrapping Up

Refactoring isn’t a magical reset button. Instead, it follows a meticulous approach to transform your codebase! A mix of best tools, techniques, and refactoring practices helps to rework the bloated code for improved speed and productivity. If you wish to refactor your complex codebase, then reach out to the coding ninjas in ISHIR. We promise to add style, flair, and simplicity for the best performance and quality.

Code Refactoring FAQs: What Developers Ask in 2025

Q1. What is code refactoring and why is it important?

A. Code refactoring is the process of improving the internal structure of existing code without changing its external behavior. It helps make the code cleaner, more efficient, and easier to maintain. Refactoring is critical for reducing technical debt, improving performance, and enabling faster feature development in growing applications.

Q2. How does code refactoring improve performance?

A. While not always aimed at performance, strategic refactoring can remove redundant operations, reduce memory usage, and optimize loops or algorithms. By restructuring inefficient code paths and cleaning up logic, refactoring can lead to faster execution, especially in performance-critical or resource-constrained applications.

Q3. What are the best practices for safe code refactoring?

A. Best practices include:

  • Backing up code or using version control (Git)
  • Writing or running unit tests before and after changes
  • Refactoring incrementally, not all at once
  • Using AI-powered tools or IDEs for intelligent suggestions
  • Reviewing changes with peers to catch regressions

Q4. Can ChatGPT or AI tools actually refactor my code?

A. Yes, tools like ChatGPT, Sourcegraph Cody, and Copilot can assist with refactoring by analyzing your code and suggesting improvements in structure, readability, and efficiency. While they’re not perfect replacements for human judgment, they’re powerful collaborators that can refactor repetitive or boilerplate logic, spot anti-patterns, and explain refactoring steps, all in natural language.