Purpose of the course

The goal of the whole course is to have fun, stay happy, and gain real Java programming skills in order to easily get a job as a programmer.

Game structure

The course consists of four main quests, and each quest consists of at least ten levels. Each level contains 10-12 lessons and 20-30 exercises. For completing tasks and some other actions, you get experience points or "dark matter". You can use it to unlock the subsequent lessons and tasks.

Advancing to the next level or lesson

To advance to the next lesson or level, you need to collect enough «dark matter» to «pay» to unlock it.

The description of each task says how many units you will receive for completing it.

For example, you’ll earn 10 particles of dark matter for the following exercise.


In CodeGym, you'll find a ton of different exercises. You get dark matter for working through them.

Copy code from an example — This is the simplest exercise. To complete it, you need to enter the Java code in the bottom of the window exactly as it appears in the top of the window.

Write a program — These are the most important tasks in the course. These can vary greatly in their complexity: all the way from short and simple tasks to puzzlers that will really put your brain to work... You can start working on any task marked as "Available". To get start one, just click the "Open" button on the task description.

This will open the Web IDE. The first tab contains the problem statement. The second tab is where you type your code. You will find the project tree on the left.

After completing a task, click the «Verify» button. You'll find out whether the task solution is correct.

If you want to just execute your program without validating it, simply click the «Run» button.

This same toolbar lets you reset your solution (in case you get confused), analyze your code (if you are studying under the Dark Grand Master), or get help with a solution.

Create a mini projects — These are the most interesting and challenging tasks! A mini-project consists of a series of interconnected sub-tasks. By the end, you will have created your very own little project. For example, some sort of game. But before you get to create your first mini-project, you’ve got a lot of work to do. You won’t see your first mini-project until Level 20.

Nerd Break — These are the hardest exercises of them all! Just kidding! Most often, a "break" involves watching a cool tech-related video. And yes, you still get a dark matter reward for these exercises too.

P.S.: Starting with Level 3, you’ll be able to work on tasks using an IDE (integrated development environment) called IntelliJ IDEA. A lesson will teach you how it’s done, but we’ll tell you more about that later.

Lessons and task statuses

Tasks can have the following statuses. Available — Go ahead and try to complete it!

«Completed» — You successfully completed this task and collected your dark matter less than three days ago. You can try to solve it again to improve your solution.

«Closed» — You successfully completed this task and collected your dark matter more than three days ago.

You can no longer submit this task for verification.

Lessons have two possible statuses: «Unlocked» and «Unavailable».

The first «unavailable» lesson after the «unlocked» lessons is the one you stopped on. If you click on it, you will be prompted to pay a certain amount of dark matter to unlock it. You can get there from the previous lesson, or you can just click on the corresponding card in the list of lessons.