Add Tutorial: Setting Up Checkstyle in IntelliJ

[arshinsikka]

We currently lack a tutorial for setting up Checkstyle in IntelliJ, even though consistent code style is a grading and PR review requirement for CS2103 projects. This issue proposes creating a new tutorial under the IntelliJ section to guide students in configuring Checkstyle correctly using the IntelliJ plugin.

This should mirror the existing VS Code - Setting up Checkstyle tutorial in structure and intent but tailored for the IntelliJ interface and plugin ecosystem.

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Proposed Tutorial Structure

Checkstyle is a development tool that helps you write clean, consistent, and readable Java code by automatically checking your source code against a set of predefined coding standards.

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Sections to Include

1. Prerequisites

   • Java and Gradle project already opened in IntelliJ
   • Checkstyle config files (checkstyle.xml and suppressions.xml) placed in config/checkstyle/
   • Ideally reuse config files from AB3

2. Installing the Checkstyle Plugin

   • Show how to install Checkstyle-IDEA from IntelliJ’s Plugins Marketplace
   • Restart IntelliJ after installing

3. Configuring the Plugin

   • Navigate to Preferences > Tools > Checkstyle
   • Add a new configuration pointing to config/checkstyle/checkstyle.xml
   • Set it as the default configuration
   • Ensure “Scan with every file save” is checked

4. Viewing Violations

   • Violations appear in the Problems tab or highlighted in-editor
   • Screenshot showing an example (e.g., wildcard import warning)

5. (Optional) Exclude Specific Files/Packages

   • Brief mention of suppressions.xml and how to link it in the config

6. Adding .idea and related folders to .gitignore

   • To avoid committing IDE-specific configs

7. Troubleshooting Tips

   • Restart IntelliJ
   • Recheck config file paths
   • Common macOS permission issues
   • Missing plugin or mislinked XML file

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Expected Assets

• Plugin install screenshot
• Preferences panel with Checkstyle config selected
• Example violation (e.g., wildcard import or line length)

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