Step-by-Step: How To Run Kotlin In IntelliJ Made Simple

If you’re eager to learn Kotlin programming and want to set up your first Kotlin project, IntelliJ IDEA is your best choice. As a robust IDE, it supports Kotlin natively and offers a user-friendly environment to get started with Kotlin.

This blog walks you through the steps to create your first Kotlin project, explaining critical configurations, tools, and the Gradle build system. By the end, you’ll know exactly how to run Kotlin in IntelliJ, even if you’re a complete beginner.

Step 1: Download and Install IntelliJ IDEA

First, you need to download and install IntelliJ IDEA from JetBrains' official website. Make sure to choose the latest version of IntelliJ IDEA, as it provides updated features and compatibility with Kotlin.

1. Go to IntelliJ IDEA download page .

2. Select the edition that fits your needs:

   • Community Edition (free, suitable for beginners).

   • Ultimate Edition (paid, for advanced features).

3. Once downloaded, install the IDE by following the on-screen instructions.

Ensure you have a necessary JDK installed (preferably the latest version). If you haven’t already:

• Download the JDK from Oracle or any trusted source.

• Specify the path of your JDK home directory during IntelliJ setup.

Step 2: Create a New Kotlin Project

After launching IntelliJ, follow these steps to create a new project:

1. On the welcome screen, click New Project.

2. In the next screen, select Kotlin under the language options.

3. Choose the Gradle build system (or IntelliJ build system, depending on your needs).

4. Check the create git repository checkbox if you plan to use version control.

5. Click Create to proceed.

Configure Kotlin Settings

• If you’re building a Kotlin Multiplatform project, select the Kotlin Multiplatform Gradle plugin. Otherwise, proceed with JVM for a standard Kotlin application.

• Add sample configurations like the add sample code option to quickly populate your project with starter code.

Step 3: Understanding the Project Structure

After creating the project, let’s explore its project structure:

• src/main/kotlin: This is where your Kotlin code resides.

• build.gradle.kts: The build script manages dependencies and the project setup.

• settings.gradle.kts: This file links your modules.

If you’re working on a more complex project, you might need to configure your build script with additional dependencies.

Example of a Basic build.gradle.kts Script

Kotlin

1plugins {
2    kotlin("jvm") version "1.8.10"
3}
4
5repositories {
6    mavenCentral()
7}
8
9dependencies {
10    implementation(kotlin("stdlib"))
11}

​

Step 4: Writing Your First Kotlin Code

Navigate to src/main/kotlin and create a new Kotlin file:

1. Right-click on the kotlin folder.

2. Select New > Kotlin File/Class.

3. Name your file (e.g., Main.kt).

Add the following sample code to print a classic hello world message:

Kotlin

1fun main() {
2    println("Hello, World!")
3}

​

The main function acts as the entry point for your Kotlin application.

Step 5: Running Your Kotlin Application

To run your program:

1. Locate the Run Tool Window at the top of IntelliJ.

2. Click on the green play button beside the main function or in the tool window.

3. View the output in the console application.

This step completes the execution of your first Kotlin program.

Step 6: Configuring Gradle and JDK

While Gradle automates tasks like building, testing, and packaging, it may require downloading additional artifacts. Ensure your necessary JDK is linked:

1. Go to File > Project Structure > SDKs.

2. Select Add JDK, then locate your JDK home directory.

3. Save changes and sync the Gradle project.

For Kotlin Multiplatform projects, include multiplatform libraries like kotlinx.

Step 7: Testing and Debugging

Testing your Kotlin code is crucial:

• Write unit tests to verify your functions.

• Add assertions to check code accuracy.

Example of a simple test:

Kotlin

1import kotlin.test.assertEquals
2import org.junit.Test
3
4class MyTests {
5    @Test
6    fun testAddition() {
7        assertEquals(4, 2 + 2)
8    }
9}

​

Run tests from the tool window or via the Run Tool Window.

Additional Tips for Beginners

• Use the onboarding tips option provided in IntelliJ to learn shortcuts.

• For a complex project, use further configuration to optimize settings.

• If you want to experiment, use the generate code feature for templates.

Wrapping Up

You’ve now learned how to run Kotlin in IntelliJ and build your first Kotlin application. Whether you’re exploring the Gradle build system, writing hello world, or delving into unit tests, IntelliJ provides all the tools you need. Remember to keep your plugins and JDK updated to the latest version for a seamless experience. Now that you’re equipped with this guide, dive into coding with confidence!

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