This document was originally written for Classroom Level 4 and hence its screenshots refer to addressbook-level4. For use with Classroom Level 3, wherever addressbook-level4 is used in the screenshots, you should use addressbook-level3.

Configuring Checkstyle-IDEA

  1. Install the Checkstyle-IDEA plugin by going to File > Settings (Windows/Linux), or IntelliJ IDEA > Preferences…​ (macOS).
    Select Plugins, press Browse Repository, and find the plugin.
    Restart the IDE to complete the installation.

  2. Click File > Settings…​ > Other Settings > Checkstyle

  3. Set Scan Scope to Only Java sources (including tests), so that the plugin will run checkstyle for our test source codes as well

  4. Ensure that the Checkstyle version is set to 8.1. This is the same version that we are using inside Gradle, so that you won’t get any errors due to version incompatibility

    • If Checkstyle version is not set to 8.1, set it to version 8.1 and click Apply

      checkstyle idea scan scope

  5. Click the plus sign under Configuration File

  6. Enter an arbitrary description e.g. addressbook

  7. Select Use a local Checkstyle file

  8. Use the checkstyle configuration file found at config/checkstyle/checkstyle.xml

  9. Click Next > Finish

  10. Mark Active for the newly imported check configuration

    checkstyle idea configuration

  11. Click OK

Troubleshooting Checkstyle-IDEA

Problem: When importing checkstyle.xml, Checkstyle-IDEA plugin complains that The Checkstyle rules file could not be parsed. …​ The file has been blacklisted for 60s.

  • Reason: checkstyle.xml is written for a particular version, but the plugin was not configured to the correct version.

  • Solution: Ensure that you have selected the correct Checkstyle version that matches the version in build.gradle and have clicked Apply, as checkstyle.xml is written for Gradle’s checkstyle.

Problem: After setting up checkstyle.xml, Checkstyle-IDEA plugin does not seem to highlight the errors / real-time scanning seems broken.

  • Reason: The plugin may not immediately run after setting it up.

  • Solution: Restart the IDE.