How do you tell ktlint in android to exclude specific paths in the project?

Excluding Paths from Ktlint in Android Projects

Ktlint is a popular code style linter for Kotlin. It helps maintain code consistency and readability. However, there are situations where you might want to exclude certain paths from Ktlint’s analysis. This could be due to legacy code, generated files, or paths containing experimental features.

Methods for Excluding Paths

1. Using the `ktlint.xml` Configuration File

The most common and recommended approach is to configure Ktlint exclusions within the ktlint.xml file. This file allows you to define specific rules and customizations for Ktlint.

Example Configuration

<?xml version="1.0" encoding="UTF-8"?>
<ktlint>
    <rules>
        <exclude>
            <path>src/main/java/com/example/project/legacy/</path>
            <path>src/generated/</path>
        </exclude>
    </rules>
</ktlint>

In the above example, Ktlint will skip analysis for files located under src/main/java/com/example/project/legacy/ and src/generated/ directories.

2. Using the `-e` Command Line Argument

Alternatively, you can exclude paths directly when invoking the Ktlint command. This method is suitable for one-time exclusion or for temporarily ignoring specific paths.

Example Command

./gradlew ktlint -e "src/main/java/com/example/project/legacy/" -e "src/generated/"

This command will run Ktlint, excluding the specified paths.

3. Using Build Tools (Gradle)

For Android projects built with Gradle, you can configure Ktlint exclusions directly within your build.gradle file. This approach integrates Ktlint with your build process and allows you to define exclusions as part of your project configuration.

Example Gradle Configuration

dependencies {
    // ... other dependencies
    implementation("com.pinterest:ktlint:0.45.2")
}

ktlint {
    android = true
    verbose = true
    debug = true
    outputToConsole = true
    filter {
        exclude("**/src/main/java/com/example/project/legacy/**")
        exclude("**/src/generated/**")
    }
}

This configuration sets up Ktlint in your project and defines the exclusion rules within the filter block.

Comparison of Methods

Choosing the Right Method

• For persistent and project-wide exclusions, use the ktlint.xml configuration file.
• For quick or temporary exclusions, use the command line argument.
• For integrated exclusions within your build process, use Gradle build tools.

Remember to choose the method that best suits your specific needs and project structure.