Adding ktlint to an Android Project

30.04.2019 — Kotlin, Android — 1 min read

If you want something to analyze your Kotlin code ktlint does the job pretty well. Unfortunately the documentation isn't that clear about how to set everything up. Here's a really quick rundown.

Adding klint to your Android Project

First create a new file in your project root called 'ktlint.gradle' and put this in it:

1repositories {
2    jcenter()
3}
4
5configurations {
6    ktlint
7}
8
9dependencies {
10    ktlint "com.github.shyiko:ktlint:0.31.0"
11    // additional 3rd party ruleset(s) can be specified here
12    // just add them to the classpath (ktlint 'groupId:artifactId:version') and
13    // ktlint will pick them up
14}
15
16task ktlint(type: JavaExec, group: "verification") {
17    description = "Check Kotlin code style."
18    main = "com.github.shyiko.ktlint.Main"
19    classpath = configurations.ktlint
20    args "src/**/*.kt"
21    // to generate report in checkstyle format prepend following args:
22    // "--reporter=plain", "--reporter=checkstyle,output=${buildDir}/ktlint.xml"
23    // see https://github.com/pinterest/ktlint#usage for more
24}
25check.dependsOn ktlint
26
27task ktlintFormat(type: JavaExec, group: "formatting") {
28    description = "Fix Kotlin code style deviations."
29    main = "com.pinterest.ktlint.Main"
30    classpath = configurations.ktlint
31    args "-F", "src/**/*.kt"
32}

After that open up your app-level build.gradle file and add the following line:

1apply from: "../ktlint.gradle"

This goes nicely under any other 'apply plugin's you already have in there. So for example:

1apply plugin: 'com.android.application'
2apply plugin: 'kotlin-android'
3apply plugin: 'kotlin-android-extensions'
4apply plugin: 'io.fabric'
5
6apply from: "../ktlint.gradle"
7
8android {
9  ...

It should ask you to sync your project, after that is done you can use the following command to run ktlint:

1./gradlew ktlint

Happy linting!