Learn Java from scratch — with every program compiled and checked
A hands-on Java course for complete beginners. You write real Java in the browser and it is compiled and tested for you — no JDK to install, no build files to fight. Short interactive lessons introduce each idea; coding challenges make it stick. By the end you know the language and the Collections Framework interviewers expect.
public class Main {
public static void main(String[] args) {
System.out.println("Hello, Java!");
for (int i = 1; i <= 5; i++) {
System.out.println(i + " squared is " + i * i);
}
}
}Why learn Java here
The language of the industry
Java runs a huge share of the back-ends you use every day, and it is standard at Amazon, most product companies and every service company. Learning it well opens a lot of doors.
Types that catch your mistakes
Java is statically typed, so the compiler flags many bugs before your program ever runs. The course leans into that — you learn to read compiler messages instead of fearing them.
The Collections Framework, taught properly
ArrayList, HashMap, HashSet, ArrayDeque — knowing which to reach for is half of real Java. A whole chapter is devoted to it, with the trade-offs made explicit.
The syllabus — 8 chapters, in order
Each chapter is a set of short interactive lessons, then coding challenges you submit to a real judge before moving on.
- 01Getting Started
- 02Decisions & Loops
- 03Arrays
- 04Methods & Sorting
- 05Working with Text
- 06Collections
- 07Classes & Objects
- 08Robust Java
What you can do by the end
- Write and run Java — variables, types, and clean System.out output
- Control flow with if/else, for and while loops
- Work with arrays and the Collections Framework (ArrayList, HashMap, HashSet)
- Write methods and sort with comparators
- Design your own classes with fields, constructors and inheritance
- Handle exceptions and use interfaces and generics
How the course works
Read a short lesson
One idea at a time, written for a beginner — with worked examples and quick-check questions, not a video to scrub through.
Write real Java
Every lesson ends in an in-browser editor. Nothing to install — you write Java and press run.
A real judge checks it
Your code is compiled and run against hidden tests, so you know it actually works instead of guessing.
Java from scratch — questions people ask
How do I learn Java from scratch?
Begin with the basics — printing, variables and types, loops — and write code at every step, then move up to arrays, the Collections Framework and object-oriented design. This course is that path: eight chapters of interactive lessons and coding challenges, each compiled and tested by a real judge.
Is this Java course free?
You can start for free with no card. A free account opens the interactive workspace and the first lessons; one membership then unlocks the whole Java course plus the Python, C++ and JavaScript courses and the full DSA course.
Do I need to install the JDK?
No. Your code is compiled and run for you in the browser, so there is nothing to set up — you write a class and press submit.
Which Java version is used?
A modern LTS Java. You will write standard, idiomatic Java that reads the way interviewers expect.
Is Java good for coding interviews?
Yes — it is one of the most common interview languages. After this course, the Data Structures & Algorithms course (also taught in Java) is included in the same membership and takes you the rest of the way.
Will I get a certificate?
Yes. Completing the course issues a certificate with a public verification link an employer can check.
Also included in your membership
One membership unlocks every course — switch between them whenever you like. Nothing here is sold separately.
Start Java today — free
A free account opens the workspace and the first lessons, no card. One membership then unlocks this course and every other — $49 a year (international price; the price for your region is shown at checkout).