How to Build an Android App with Kotlin: A Step-by-Step Tutorial

Kotlin has become the go-to language for Android development — concise, safe, and fully supported by Google. Whether you’re a beginner or switching from Java, building your first app is straightforward. This tutorial walks you through the essential steps to create a functional Android app using Kotlin and Android Studio.

1. Set Up Your Development Environment

First, download and install Android Studio (the official IDE). During installation, ensure the Android SDK and Kotlin plugin are included. Once installed, open Android Studio and select “New Project.” Choose a template like “Empty Activity” — this gives you a ready-made Kotlin project structure.

2. Understand the Project Structure

Your project contains two key folders: java (or kotlin) for Kotlin source files, and res for resources. The main activity (e.g., MainActivity.kt) is where your Kotlin code lives. The layout file (activity_main.xml) defines the UI. You’ll edit both to build your app.

Key Files You’ll Use

• MainActivity.kt — app logic
• activity_main.xml — UI layout
• AndroidManifest.xml — app configuration

3. Build a Simple UI with XML

Open activity_main.xml and add a TextView and Button inside a LinearLayout. Give them IDs like tvHello and btnClick. Use wrap_content for sizing and a simple vertical orientation. This creates a clean interface without complex code.

4. Write Kotlin Code to Make It Interactive

In MainActivity.kt, reference the views using findViewById or the by viewModels() delegate. Set an setOnClickListener on the button to update the text. Here’s a minimal example:

val btn = findViewById<Button>(R.id.btnClick)
btn.setOnClickListener {
    findViewById<TextView>(R.id.tvHello).text = "Hello, Kotlin!"
}

Run your app on an emulator or device by clicking the green play icon. You’ll see the button change the label instantly.

Conclusion

You’ve just built your first Android app with Kotlin! From here, explore modern UI with Jetpack Compose, add ViewModels for data handling, or connect to APIs. The official Android documentation is your best next resource. Happy coding!