How to change line separator in IntelliJ?

Changing line separators in IntelliJ IDEA is a straightforward process, crucial for maintaining code consistency across different operating systems. You can easily adjust line endings for a single file, an entire project, or set a default for new files.

Understanding Line Separators

Line separators, or line endings, are special characters that mark the end of a line in a text file. Different operating systems use different conventions, which can sometimes lead to issues when collaborating on projects across platforms:

LF (Line Feed, \n): Used by Unix, Linux, and macOS.
CRLF (Carriage Return Line Feed, \r\n): Used by Windows.
CR (Carriage Return, \r): Used by classic Mac OS (prior to macOS X), now rarely encountered.

Ensuring consistent line endings prevents problems like unnecessary diffs in version control systems or syntax errors in certain build tools.

Methods to Change Line Separators in IntelliJ

IntelliJ IDEA offers several ways to modify line separators, catering to different needs:

1. For the Current File Using the Status Bar Widget

This is the quickest way to change the line ending style for the file currently open in your editor.

Open the File: Open the file you want to modify in the IntelliJ editor.
Locate the Widget: Look for the line separator widget in the status bar at the bottom right of the IDE window. It typically displays the current line ending style, e.g., "LF," "CRLF," or "CR."
Select New Style: Click on the widget. A small pop-up menu will appear, allowing you to choose between "LF," "CRLF," or "CR." Select your desired line separator style.
- Example: If your file shows "CRLF" and you want to switch to Unix-style, click "CRLF" and then select "LF."

2. For the Current File Using File Properties

Another way to adjust line separators for an open file is through the file properties menu.

Open the File: Ensure the target file is open in the editor.
Navigate to File Properties: Go to File in the top menu bar.
Select Line Separators: Hover over File Properties, then click Line Separators.
Choose Style: From the submenu, select the desired line ending style (e.g., LF - Unix and macOS, CRLF - Windows).

3. For an Entire Project (or a Directory)

To ensure consistency across an entire project or a specific directory, you can change the line separators for multiple files at once.

Select Files/Directories: In the Project tool window, select the files or directories you want to modify. You can select multiple items by holding Ctrl (Windows/Linux) or Cmd (macOS) and clicking.
Access Line Separators: Right-click on the selection.
Choose Action:
- Select Line Separators from the context menu.
- Alternatively, go to File | Line Separators from the top menu after selecting items.
Apply Style: Choose your preferred line ending style (e.g., LF for Unix/macOS projects). IntelliJ will then apply this setting to all selected files.

4. Setting the Default Line Separator for New Files and Projects

To prevent line separator issues from the start, you can configure IntelliJ IDEA to use a specific line ending by default for all new files or new projects.

Open Settings/Preferences:
- Windows/Linux: Go to File | Settings.
- macOS: Go to IntelliJ IDEA | Preferences.
Navigate to Code Style: In the settings dialog, expand Editor and select Code Style.
Set Line Separator: On the General tab (usually the default), locate the Line separator dropdown.
Choose Default: Select your desired default line ending (e.g., Unix and macOS (\n)).
Apply Settings: Click Apply and then OK to save your changes.
- Tip: This setting applies to new files created within projects that inherit this default. Existing files retain their current line endings unless explicitly changed.

For New Projects:

When creating a new project, IntelliJ often gives you an option to set the project-specific line separators, or it defaults to the global setting you've configured. Always check the project creation wizard for line ending options.

Practical Considerations and Best Practices

Version Control Systems (VCS): If you're using Git, be mindful of Git's core.autocrlf setting, which can automatically convert line endings on commit or checkout. It's often recommended to set core.autocrlf to input on Linux/macOS and true on Windows, or false everywhere and let your IDE handle it consistently.
Team Collaboration: Discuss and agree upon a consistent line separator standard with your team to avoid conflicts and maintain a clean codebase.
Mixed Environments: If your team uses both Windows and Unix-like systems, standardize on LF as it's generally more compatible across platforms and less prone to causing issues.
Hidden Characters: If you ever need to visually check line endings, IntelliJ IDEA allows you to show "Whitespace" characters (View | Active Editor | Show Whitespace). This will display LF as a small dot and CRLF as \r\n.

Common Line Separator Styles

Line Separator	Symbol	Operating Systems	Description
LF	`\n`	Unix, Linux, macOS	Line Feed. Most common in modern development.
CRLF	`\r\n`	Windows	Carriage Return + Line Feed. Traditional Windows.
CR	`\r`	Classic Mac OS	Carriage Return. Rarely used today.

By mastering these simple steps, you can ensure your IntelliJ projects maintain consistent and compatible line endings, streamlining your development workflow and collaboration efforts.