Choosing an IDE for Kotlin: IntelliJ IDEA, Android Studio, VS Code

1. What an IDE is

IDE (Integrated Development Environment) is not just a trendy word programmers like to repeat. It is an entire toolchain for development: a code editor, a compiler, a debugger, a hint/suggestion system, project management, and even a built-in coffee machine… well, okay, that last one does not exist yet.

Why is an IDE more convenient than a text editor + command line?

When you write code in a regular editor (Notepad or Vim), you have to manually run compilation, search for errors in the console, and sometimes even remember which folder contains the file you need. An IDE does all of this for you — and a little bit more:

• errors are visible immediately, not after compilation;
• the IDE suggests methods, variables, and sometimes even seems to read your mind;
• no need to switch between windows;
• you can instantly jump to the class, function, or file you need;
• integration with version control systems (Git);
• adding external libraries is just a couple of clicks.

Writing code in a plain editor is like assembling IKEA furniture blindfolded; an IDE is like assembling the same furniture with an experienced craftsman and a full set of automated tools.

2. Overview of popular IDEs for Kotlin

In the Kotlin world, the choice of a development environment is a bit different than for some other languages. Since the language was created specifically for modern programming, there are a few main tools:

IntelliJ IDEA

• Recommended for our course and for all beginners.
• Starting with version 2025.3, it became a single product: everything you need for development is available for free with no limitations.
• Kotlin and IntelliJ IDEA are developed by the same company (JetBrains). That means new language features show up here immediately and work flawlessly.
• Support for the latest language versions (including the new ultra-fast K2 compiler).
• A powerful system of hints, autocompletion, and refactoring (automatic safe code rewriting).
• A pleasant modern interface (New UI) that does not intimidate beginners.

Android Studio

• If you plan to write Android mobile apps, this will be your primary tool in the future.
• Built on the IntelliJ IDEA platform, so the interface and hotkeys will feel familiar.
• Optimized for mobile development specifics (phone emulators, screen layouts).
• For learning basic console Kotlin (Kotlin/JVM) in our course, it is overkill and more “heavyweight” than regular IDEA.

Visual Studio Code (VS Code)

• It is more of a “super editor” than a full IDE out of the box.
• For comfortable Kotlin work, it requires installing extra extensions (for example, Kotlin Language Server).
• Great for weaker computers or for writing simple scripts.
• For deep learning and serious Kotlin/JVM server-side development, it often falls short of IntelliJ IDEA in terms of code analysis and configuration convenience.

3. An alternative for quick tests

Sometimes you only need to check a couple lines of code — for example, to recall how a specific function works or to quickly test a math formula. Launching a full IDE or creating a new project can be unnecessary for that.

In such cases, play.kotlinlang.org is a great help. It is the official online sandbox from the language creators.

• Pros: works right in the browser, requires no installation, lets you run code instantly, and makes it easy to share via a link (very convenient if you want to show your code to a mentor).
• Cons: it is not an IDE. There is no project structure, advanced suggestions, debugger, or the ability to connect third-party libraries or read files from your computer.

For full-scale learning and project work, the sandbox is not suitable, but as a “write-test-forget” tool, it is perfect.

4. Why we choose IntelliJ IDEA

If you ask any professional Kotlin developer, “Where should I start?”, in 99 out of 100 cases they will recommend IntelliJ IDEA. Why?

• Perfect synergy: the tool and the language come from the same creators.
• Beginner-friendly simplicity: you do not spend hours installing plugins — create a project and everything just works.
• Advanced Git integration.
• Smart static analysis system (the IDE “understands” your code).

JetBrains Junie AI agent

IntelliJ IDEA has JetBrains Junie built in — not just a smart assistant, but a full AI agent.

Unlike regular autocompletion, Junie understands the context of your entire project. It can independently find the cause of an error, suggest how to modernize old code, or even generate tests.

Junie is a powerful tool, but for a beginner it is a double-edged sword. Use it to ask it to explain a tricky piece of code (“Junie, what does this line do?”), but try to solve tasks on your own. In a job interview, you will not have an AI agent with you.

Autocompletion

People sometimes say, “IDEA writes the code for you.” That is, of course, an exaggeration… but when you see autocompletion in action for the first time, you will understand why developers love this tool so much.

Autocompletion example

You simply start typing a word, and the IDE immediately offers options to complete it. To quickly select the needed option, the “Tab” or “Enter” key is most often used.

printl // IDEA will suggest options: println, print, etc.
readl  // will suggest readln(), readlnOrNull()

5. Code analysis in an IDE: errors before compilation

When people say “IDE shows errors,” beginners often think about the moment you run (compile). In reality, IntelliJ IDEA performs static analysis — it continuously reads and analyzes your code as you type, even before you press the Run button ▶.

Let’s take an example. Suppose you declared a variable for age, but accidentally tried to assign a string to it instead of a number:

fun main() {
    val age: Int = "Twenty" // Type error!
}

In a plain text editor, you would only find out after trying to run the program. In IntelliJ IDEA, the word "Twenty" will be underlined in red instantly. The IDE will explain in human language: Type mismatch: inferred type is String but Int was expected (Type mismatch: Int was expected, but a string was found).

This is not the program nitpicking — it is real help that prevents you from running code that is guaranteed not to work.

6. Early diagnostics: the problem is visible before it becomes a mystery

One of the most painful situations at the start of learning is: “I pressed Run, and it does not work, and I do not understand where.” An IDE turns invisible errors into obvious ones.

For example, a common mechanical typo in a function name:

fun main() {
    prinln("Hello, Kotlin!") // the letter 't' is missing
}

The name prinln will immediately turn red. This is incredibly important psychologically: you catch the typo right away, with your eyes, before your brain starts inventing complex theories about why “Kotlin broke.”

In addition to red errors (which prevent the program from running), the IDE shows warnings (in gray or yellow). For example, you created a variable but never used it anywhere. The program will work, but the IDE will highlight the variable name in gray, hinting: “Looks like there is some leftover junk here, or you forgot to finish the logic”. Getting into the habit of paying attention to development environment hints is one of the main steps from intern to Junior developer.