Introduction to Kotlin in 2025: Where to Start for Beginners

Introduction to Kotlin: Where to Start in 2025

Kotlin is a modern, statically typed programming language that runs on the JVM (Java Virtual Machine) platform. Developed by JetBrains, Kotlin quickly gained popularity due to its conciseness, safety, and full compatibility with Java. If you're looking for where to start learning programming in 2025, Kotlin is an excellent choice. It is used for creating Android applications, server-side solutions, web applications, and even cross-platform projects.

In this article, we will cover the main steps for beginners: tool installation, first code, basic syntax, and key language features. By the end, you will be able to write your first program and understand where to go next.

Why Kotlin in 2025?

Kotlin is officially supported by Google for Android development and is actively used in large companies such as Pinterest, Uber, and Netflix. In 2025, the language continues to evolve: new versions are released with improved performance and support for modern paradigms. Here are the main reasons to choose Kotlin:

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• Conciseness: Kotlin code is on average 40% shorter than Java code.
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• Null safety: The type system prevents errors related to null references.
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• Java compatibility: You can use all Java libraries and frameworks.
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• Multiplatform: Write code once and run it on Android, iOS, web, and desktop.
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• Active community: Plenty of learning materials, forums, and open-source projects.
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Installation and Development Environment Setup

To start working with Kotlin, you will need the JDK (Java Development Kit) and an IDE. We recommend using IntelliJ IDEA Community Edition — it is created by the same team that built Kotlin.

Step 1: Install JDK

Download the latest JDK version from the official Oracle website or use OpenJDK. Install it and check the version in the terminal:

java -version

You should see something like openjdk version "21.0.1" 2025-01-18.

Step 2: Install IntelliJ IDEA

Download IntelliJ IDEA Community Edition from the JetBrains website. The installation is standard — just follow the instructions. After launching, select "New Project" and in the language list choose Kotlin. The IDE will automatically configure everything needed.

Step 3: Create Your First Project

Create a new project, select the "Console Application" template. IntelliJ IDEA will create a Main.kt file with ready-made code. Run it — you will see "Hello, World!" in the console. Congratulations, your environment is ready!

Kotlin Syntax Basics for Beginners

Kotlin has an intuitive syntax. Let's break down the key constructs with examples.

Variables and Data Types

Variables are declared using the keywords val (immutable) and var (mutable). The type can be specified explicitly or omitted — the compiler will infer it.

fun main() {\n    val name: String = "PythonLib"  // Immutable string\n    var age = 2025                  // Mutable number, type Int inferred automatically\n    println("Hello, $name! It is $age year.")\n    \n    age = 2026                      // Can be changed\n    println("Next year it will be $age year.")\n}

Conditional Statements

Kotlin uses standard if and when (analogous to switch in Java).

fun main() {\n    val score = 85\n    if (score >= 80) {\n        println("Excellent!")\n    } else {\n        println("Try again.")\n    }\n    \n    // Using when\n    val grade = when {\n        score >= 90 -> "A"\n        score >= 80 -> "B"\n        else -> "