To ensure that all Kotlin files in a commit conform to
the Kotlin Style Guide, the code formatter Ktlint is used in the
project. This code formatter is integrated in the build pipeline via
the Spotless plugin.
So, the local build of the project as well as the build pipeline will fail if a Kotlin file is not formatted
properly.
If the local build fails, you have the opportunity to auto format all files with a format violation with the following command:
./gradlew spotlessApplyHint: It is possible that spotlessApply can't fix all violations in your commit. E.g, if you have a wildcard
import, spotlessApply won't be able to correct the imports by itself. In this case, you will receive an error message
with the Kotlin file that has a format violation.
Also, the execution of
./gradlew buildfails and shows you the error message with the format violation.
To avoid failing builds, the formatting config of your IDE should be set properly. The recommended preferences are described in the following.
As described in the Kotlin Style Guide, wildcard imports should be avoided. To configure this in IntelliJ, you have to
navigate in the Preferences to:
Editor > Code Style > Kotlin
Make sure that you choose the option "Use single name import"
for the sections Top-Level Symbols and Java Statics and Enum Members.
Also, you should remove all values from the section Packages to Use Import with "*"
so that this table is empty, as shown in the screenshot below:
Furthermore, you have to install the Plugin "Save Actions". After the installation, tick the following options:
- Activate save actions on save (before saving each file, performs the configured actions below)
- Optimize imports
- Reformat file
To avoid unwanted reformattings of markdown files, you should exclude these files by the following path:
.*\.mdAdd this path to the section File Path Exclusions as shown below:
