The Ultimate Gradle Kotlin Beginner's Crash Course For 2025

What is Gradle?

This is a crash course for developers building software in modern, efficient ways on Gradle with Kotlin. The tutorial has been created to take beginners from the ground to working on their projects with confidence, providing knowledge of how to apply build automation using Gradle's Kotlin DSL.

1.  What is Gradle?

• Gradle is an automation build tool used for software development. It's very famous for Java, Kotlin, and Android but supports lots of languages. Gradle automates tedious tasks, such as compilation of the code, application packaging, running tests, and managing dependency.

2. Why Kotlin DSL for Gradle?

• Gradle was originally built as a Groovy-based product, but it has support for Kotlin DSL as its alternative. Why use Kotlin DSL?

  
  

• Type Safety:- enjoy auto-completion and even type-checking in the IDE.

• Readability:- Kotlin is modern and concise, yet very highly expressive.

  
  

• Consistency:- if you already program in Kotlin, then of course you'll want to follow up with Kotlin for building your build scripts.

3.  Installing Gradle

• Install Java:- Gradle needs to run Java. Install the latest JDK if it is not already installed.

  
  

• Download Gradle:- Use a package manager or download it manually.

  
  

• Mac:- brew install Gradle.

  
  

• Windows:- Use Chocolatey or download the installer.

  
  

• Linux:- Use your distribution's package manager or install manually.

Verify installation

gradle --version

4. Creating a New Gradle Project

Step 1: Create a Project

Run:

gradle init

Select:

• Type: Application

• Language: Kotlin

• Build Script DSL: Kotlin DSL

This will produce a directory structure with the following files:

• build.gradle.kts (Kotlin DSL build script)

settings.gradle.kts

Step 2: Explore the Structure

• src/main/kotlin: Application source code.

Test Code

src/test/kotlin: 

Main build script.

build.gradle.kts: 

5. Understanding

Here’s a basic Kotlin DSL script:

plugins {

    kotlin("jvm") version "1.9.0"

    application

}

repositories {

    mavenCentral()

}

dependencies {

    implementation("org.jetbrains.kotlin:kotlin-stdlib")

    testImplementation("org.jetbrains.kotlin:kotlin-test")

    testImplementation("org.jetbrains.kotlin:kotlin-test-junit5")

}

application {

    mainClass.set("com.example.AppKt") // Specify your main class here

}

Explanation

• plugins:- Add required plugins, for instance, the Kotlin or Application plugin.

  
  

• repositories:- Specify where Gradle will fetch dependencies from, for example, Maven Central

  
  

• dependencies:- Define your project's libraries

  
  

• application:- Configure main application entry point.

6. Running Tasks

Gradle tasks automate various steps in your workflow. Common tasks:

gradle build          # Compile and package your application

gradle run            # Run the application

gradle test           # Run tests

gradle clean          # Clean the build directory

gradle dependencies   # View dependency tree

7. Adding Dependencies

Dependencies are libraries or frameworks your project needs. Add them under dependencies:

dependencies {

    implementation("com.squareup.okhttp3:okhttp:4.11.0") // Example library

}

Run

gradle dependencies

to ensure the dependency is resolved.

8.  Multi-Module Projects

A multi-module project is split into multiple subprojects, each with its own build script.

root/
  ├── build.gradle.kts
  ├── settings.gradle.kts
  ├── app/
  │   ├── build.gradle.kts
  ├── library/
      ├── build.gradle.kts

settings.gradle.kts:

rootProject.name = "MyMultiModuleProject"
include("app", "library")

9. Debugging and Optimizing Builds

1. Debug a build script

gradle --debug

2. Visualize dependencies

gradle dependencies --scan

Optimize builds

• Use the Gradle Daemon for faster builds.

  
  

• Avoid unnecessary tasks with gradle build --exclude-task.

10. Resources for Continued Learning

• Official Gradle Kotlin DSL Documentation

  
  

• Gradle Tutorials

  
  

• Kotlin Reference

By the end of this crash course, you should have a solid foundation to work with Gradle using Kotlin DSL. Happy building.