Installing the JavaRush plugin for IntelliJ IDEA

1. How to find and install the JavaRush plugin

If IntelliJ IDEA were a smartphone, then plugins would be the apps that make it truly useful. Plugins extend the IDE’s functionality: they add support for new languages, integration with services, tools for code inspection, and even mini-games (but it’s best not to get carried away with the latter when you have a deadline).

The JavaRush plugin is a special extension created so that you can solve course tasks directly in IntelliJ IDEA. Imagine: no need to copy code back and forth, no need to constantly switch between the browser and the IDE—everything works in one window! The plugin lets you:

• Receive Kotlin tasks right in the project;
• Submit solutions for review with a single click;
• Immediately see the result: accepted, error, hint;
• And, of course, get distracted by cats in the browser less often (well, almost).

2. Installing and activating the JavaRush plugin

To work with the plugin, you will need version 2025.1 or newer. The CodeGym plugin version must be 251.1.16 or newer.

You can download the JavaRush plugin from the JetBrains Marketplace.

1. Go to “Settings”: Windows/Linux File - Settings, macOS Intellij IDEA - Preferences. If you don’t have the settings section, open any project or create a new one.
2. In the window that appears, in the side menu select Plugins and open the Marketplace tab. In the search field, type javarush.

3. Select the plugin, click Install, and accept the “Third-Party Plugins Notice”.

4. Restart IntelliJ IDEA (Restart IDE) to start using the plugin.

5. You will see a slightly updated interface and a Sign in to account button on the top horizontal panel.

   Clicking it will open a sign-in window for your account, where you need to enter your secret key. You can find the key in “Settings” → “Security and sign-in”.

   After logging in, the project and the Javarush SDK will start downloading (it is not recommended to change it to a different version).

   Trust and Open... is a security feature notification in IntelliJ IDEA (Project Security). Essentially, IntelliJ IDEA is asking whether you trust this project. For JavaRush projects, you can safely click "Trust Project".

6. To open a new task, click Tasks on the left vertical panel, then click the task card in the side panel on the left, and in the pop-up window click Open:

   You will see a window with two tabs. Solution is the task file, and Condition is the description.

   Enter your solution and click the Check button.

"Unresolved reference" or "Kotlin is not configured" errors and configuring Kotlin

After you have received a project from the server and opened the task file, you may find that basic commands are highlighted in red with an Unresolved reference error. The project will not run.

This happens because the standard language library has not yet been added to the project. In older versions of IntelliJ IDEA, a yellow Kotlin is not configured panel appeared for this, but in newer versions, the environment must be configured manually.

Why is manual configuration required?

Kotlin is a cross-platform programming language. This means that the source code can be:

• Compiled to run on the Java Virtual Machine (JVM).
• Transpiled into JavaScript or native applications.

Since the project has just been downloaded from the server, IntelliJ IDEA requires the developer to explicitly specify for which target environment Kotlin needs to be configured.

Step-by-step configuration setup ⚙️

1. In the top main menu of IntelliJ IDEA, click on ☰ and follow the path: Tools → Kotlin → Configure Kotlin in Project.
2. In the dialog box that appears, select Java (or Java/JPS). We make this choice because we use a local JDK, and our code will be compiled to run under the JVM. Then click OK.
3. Wait for the process to complete. IntelliJ IDEA will automatically download and add the Kotlin standard library (KotlinJavaRuntime) to your project.
4. After a successful setup, the red error highlighting will disappear, and an active green program execution button (Run) will appear to the left of the main function.

You can now solve tasks.

Task synchronization: website — plugin

The list of tasks and their statuses is updated automatically every five minutes, or after submitting any task for review (it must be successful).

Therefore, if you solved a task on the website, it will also appear in the plugin in the list of solved tasks. If you need to refresh task status information right now, click your avatar (top right), and in the drop-down menu select Sync tasks:

Beginner mode in the plugin

This is a simplified version for users who have no (or little) experience with IntelliJ IDEA and other development environments. Some IntelliJ IDEA features are hidden in it. To disable this mode, click your avatar (top right), and in the drop-down menu select Settings -> Beginner Mode.

How to hide the plugin navigation panel in PRO mode

Click Settings (⚙️) and uncheck “Show plugin navigation panel”:

4. Plugins for IntelliJ IDEA

IntelliJ IDEA has many plugins that make different aspects of a developer’s work easier. But we’re primarily interested in those that help us learn and make work more enjoyable.

1. Key Promoter X

There’s an absolutely great plugin for IntelliJ IDEA called Key Promoter X. It shows you how various complex actions you perform in IDEA with the mouse can be done with a single keyboard shortcut. Install it—you won’t regret it.

2. Rainbow Brackets

Rainbow Brackets is a plugin that colors matching parentheses (round, square, and curly) in different colors. When you have many nested brackets, it’s very easy to get confused. The plugin helps you quickly determine which bracket matches which.

3. Material Theme UI

Want your IDE to look stylish and modern? Material Theme UI is the most popular plugin for customizing the interface. It replaces the standard IntelliJ IDEA look with beautiful Material Design themes, changes folder and file icons, and adds bright accents. This does not affect your code in any way, but it makes the work process much more enjoyable visually.