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Groovy & Gradle: JVM Automation and Build Engineering · Lesson

Writing Custom Tasks in Kotlin DSL

Create reusable, typesafe custom Gradle tasks using the Kotlin DSL, with typed properties, lazy configuration, and clean registration patterns.

Writing Custom Tasks in Kotlin DSL is a free Groovy & Gradle: JVM Automation and Build Engineering lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Groovy & Gradle: JVM Automation and Build Engineering learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Why Custom Tasks?

Built-in tasks cover common work, but real builds need project-specific automation: code generation, asset processing, custom checks. The Kotlin DSL makes these typesafe and readable.

Ad-hoc Task Registration

The simplest task is registered inline with an action block.

tasks.register("hello") {
    doLast {
        println("Hello from Gradle")
    }
}

register vs create

Prefer register over create: registration is lazy, so the task is only configured if it is actually needed, improving configuration time.

Typed Task Classes

For reusable logic, define a class extending DefaultTask with an annotated action.

abstract class GreetTask : DefaultTask() {
    @TaskAction
    fun run() {
        println("Hi")
    }
}

Typed Properties

Use Gradle Property types for lazy, configurable inputs that integrate with the build model.

abstract class GreetTask : DefaultTask() {
    @get:Input
    abstract val name: Property<String>
}

Registering a Typed Task

Register the class and configure its properties in the Kotlin DSL with full type checking.

tasks.register<GreetTask>("greet") {
    name.set("Ada")
}

Inputs and Outputs

Annotate properties so Gradle can make the task incremental and cacheable.

@get:OutputFile
abstract val report: RegularFileProperty

Lazy Configuration

Lazy Provider values defer computation until needed, avoiding work during configuration and enabling correct task dependencies.

val versionProvider = providers.gradleProperty("appVersion")

Wiring Task Dependencies

Express order with dependsOn, or better, wire outputs of one task into the inputs of another so Gradle infers the order.

tasks.register("publishDocs") {
    dependsOn("generateDocs")
}

Reusing Across Modules

Move the task class into buildSrc or a convention plugin so every module can register it without duplication.

Kotlin DSL Advantages

Compared to Groovy, the Kotlin DSL gives:

  • IDE autocompletion and refactoring
  • Compile-time error detection
  • Easier navigation to task sources

Quick Check

Test your understanding of custom tasks.

Recap

You learned custom tasks in Kotlin DSL:

  • Use lazy register over create
  • Define typed tasks extending DefaultTask
  • Use Property and annotations for typed inputs/outputs
  • Reuse via buildSrc or convention plugins

Frequently asked questions

Is the “Writing Custom Tasks in Kotlin DSL” lesson free?

Yes — the full text of “Writing Custom Tasks in Kotlin DSL” is free to read here on the web, and the Groovy & Gradle: JVM Automation and Build Engineering course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Groovy & Gradle: JVM Automation and Build Engineering course, upgrade to CoddyKit PRO.

What will I learn in “Writing Custom Tasks in Kotlin DSL”?

Create reusable, typesafe custom Gradle tasks using the Kotlin DSL, with typed properties, lazy configuration, and clean registration patterns. You practise Groovy & Gradle: JVM Automation and Build Engineering with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Groovy & Gradle: JVM Automation and Build Engineering?

No prior experience is required. Groovy & Gradle: JVM Automation and Build Engineering on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Writing Custom Tasks in Kotlin DSL” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Groovy & Gradle: JVM Automation and Build Engineering lesson?

Yes. Every Groovy & Gradle: JVM Automation and Build Engineering lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

  1. Kotlin DSL for Gradle
  2. Polyglot Project Builds
  3. IDE Integration & Tooling
  4. Writing Custom Tasks in Kotlin DSL
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