How to use IntelliJ IDEA Code Refactoring Tools

Edited 3 weeks ago by ExtremeHow Editorial Team

IntelliJ IDEA Refactoring Tools Development Programming IDE Coding IntelliJ Code Quality Software Development Productivity Source Code Application Development Project Projects

This content is available in 7 different language

IntelliJ IDEA is one of the most popular integrated development environments (IDEs) used by developers around the world. It is known for its robust features that facilitate easy code development and refactoring. In programming, refactoring is a technique that helps to change the code without changing its external behavior. It is an important aspect of software development as it helps to improve the structure, readability, and maintainability of the code. IntelliJ IDEA provides a comprehensive suite of tools to aid in this process. In this guide, we aim to explore these code refactoring tools in great detail, covering their features, how to use them, as well as practical examples.

Understanding refactoring
Before diving into the tools, it is essential to understand what refactoring is. In software development, you often need to modify, optimize, or improve your codebase. This process is called refactoring. It helps to clean up the code, reduce complexity, and make it easier for everyone to read and understand. Refactoring is important because it enables adding new features or fixing bugs without risking the overall health of the codebase.

Refactoring can include changes like renaming variables, removing methods, optimizing imports, and more. Now, let's see how IntelliJ IDEA helps you with these tasks.

Why use IntelliJ IDEA for refactoring?
IntelliJ IDEA offers a rich set of features when it comes to supporting code refactoring. With its intelligent suggestions, integration, and automation capabilities, refactoring becomes not only a necessity but also a seamless experience. Here are some reasons why you should consider IntelliJ IDEA for code refactoring:

Support for common refactorings: It supports commonly used refactorings like renaming, removing, inlining, moving, etc.
Automation: Automates repetitive refactoring tasks, ensuring speed and accuracy.
Instant Preview: Provides a live preview of changes in the codebase.
Error detection: Detects potential errors or conflicts during refactoring.

Different types of refactoring in IntelliJ IDEA
IntelliJ IDEA provides a variety of refactoring techniques. Below are some of the main types:

Renaming: Changing the names of variables to reflect their meaning.
Extraction method: Moving a block of code into a separate method.
Inline method: Replacing a method call with its contents.
Transfer: Moving classes or methods to other packages or classes.
Change signature: Modifying method signatures, such as parameter lists.
Extracting/Inlining Variables: Creating or decomposing variables.
Introduction to constants: Defining constants from literals.

Now, let's look at each of these refactorings and see how IntelliJ IDEA helps you with them.

1. Rename refactoring
Renaming is probably one of the most frequently performed refactorings by developers. It plays a vital role in achieving self-documenting code. IntelliJ IDEA simplifies the renaming process and ensures that the entire codebase remains consistent.

To rename a variable, method, class, or package in IntelliJ IDEA:

Select the entity whose name you want to change. For example, place the cursor on the variable name.
Press Shift+F6 (Windows/Linux) or Cmd+Shift+F6 (macOS).
Type the new name and press Enter.

IntelliJ IDEA automatically prompts for renames throughout the codebase, ensuring that all references to the old name are updated.

2. Extract method refactoring
Sometimes, it is helpful to break down a complex piece of logic into smaller methods to improve readability and reusability. Extract Method refactoring allows you to do this by turning a selection of code into a new method.

To use the Extract method in IntelliJ IDEA:

Select the code block you want to remove.
Press Ctrl+Alt+M (Windows/Linux) or Cmd+Alt+M (macOS).
Enter the method name and adjust the visibility as needed.
Confirm refactoring.

The IDE automatically generates methods and replaces selected code blocks with method calls, ensuring consistency.

3. Inline method refactoring
This technique is the opposite of Extract Method. If the code of a method is very simple or is used only once, you may decide to inline it. This action replaces all calls to the method with its code.

To inline a method in IntelliJ IDEA:

Place your cursor on the method name.
Press Ctrl+Alt+N (Windows/Linux) or Cmd+Alt+N (macOS).
Confirm the changes.

The IDE then replaces all calls to the method with the method contents.

4. Move refactoring
Move refactoring lets you move classes, interfaces, methods, and fields to other files or packages, helping to better organize code.

To move an element in IntelliJ IDEA:

Right-click on the element (class, method, etc.) or use F6 key.
Select the destination package or class.
Click 'Refactor' to finalize the transfer.

IntelliJ IDEA adjusts the imports and uses the correct package paths.

5. Change signature refactoring
When a method's parameters, return type, or access level needs to be changed, IntelliJ IDEA's change signature helps update the method definition as well as all its uses.

To change the method signature in IntelliJ IDEA:

Select the method name and press Ctrl+F6 (Windows/Linux) or Cmd+F6 (macOS).
Modify the method's parameter list, return type, etc.
Apply changes.

The IDE automatically updates all references to the method, ensuring compatibility.

6. Extract variable refactoring
This feature allows you to simplify long expressions by splitting them into variables with meaningful names.

To remove a variable:

Select the expression you want to restructure into variables.
Use Ctrl+Alt+V (Windows/Linux) or Cmd+Alt+V (macOS).
Name the new variable and confirm the refactoring.

IntelliJ IDEA introduces variables and replaces expressions with variables, thereby simplifying the code.

7. Introduce constant refactoring
If you use a constant value repeatedly in your program, it is a good idea to extract it as a constant. This step improves maintainability and readability.

To introduce constants in IntelliJ IDEA:

Select the value or expression that you want to extract as a constant.
Press Ctrl+Alt+C (Windows/Linux) or Cmd+Alt+C (macOS).
Enter the name of the constant and confirm.

This action creates a new constant field and replaces occurrences of the value with the new constant, thus maintaining consistency.

Committing and previewing a refactoring
IntelliJ IDEA encourages safe refactoring, providing previews for visual confirmation. You can review changes before the final commit, which helps avoid mistakes. The preview feature shows how your edits affect your code, providing version control integration for seamless management of changes.

Refactoring previews can be prompted by checking 'Show refactoring preview' during any refactor. Additionally, changes can be committed directly using the intuitive Git integration.

Dealing with conflicts and errors
Sometimes, refactoring can result in conflicts or errors, usually due to dependencies or linkages in files. IntelliJ IDEA's built-in error detector flags such issues during the refactoring process itself. The IDE provides suggestions or solutions, often integrating them automatically, increasing safety and reliability in handling large projects.

Customizing refactoring options
IntelliJ IDEA allows you to customize refactoring preferences such as naming conventions, visibility changes, etc. through its settings panel. Adjusting these settings ensures that the refactoring is aligned with team guidelines and personal preferences.

Final thoughts
Refactoring means making complex code manageable and maintainable. IntelliJ IDEA's toolset makes this process not only accessible but also enjoyable, helping developers structure, clean up, and enhance their code with confidence. Adopting these refactoring practices ensures that your code evolves into a robust, performance-friendly system.

If you find anything wrong with the article content, you can

How to use IntelliJ IDEA Code Refactoring Tools

Comments

How to use IntelliJ IDEA Code Refactoring Tools

Search ExtremeHow (en)