CS IllustratedStart practising

AP Computer Science A

Learn Java by writing every line of it yourself.

A full AP CSA course built like a notebook: watch a short lesson, type the code by hand, and run it against real tests. No copying, no shortcuts — which is exactly why it sticks.

No account needed. Nothing you write is sent to us — your progress stays in this browser.

Main.javaRan successfully
Java
public class Main {
    public static void main(String[] args) {
        for (int i = 1; i <= 10; i++) {
            System.out.println(i);
        }
    }
}

Output

1 2 3 4 5 6 7 8 9 10

How a lesson goes

1

Watch the lesson

Short videos that show the idea being used, not just defined. Pick up where you left off, on any machine.

2

Type the code yourself

Every character is yours. The editor accepts code you wrote and refuses code you did not, so the practice is real practice.

3

Run it against hidden tests

Your program compiles and runs in about a second, then gets checked against cases you cannot read ahead of time.

What you will cover

Four units, following the College Board sequence. Each one ends with code you wrote from scratch.

Unit 1

Using Objects and Methods

Variables, types, and calling the methods someone else already wrote.

Unit 2

Selection and Iteration

if, else, and the loops that do the work for you.

Unit 3

Class Creation

Writing your own classes, constructors, and instance methods.

Unit 4

Data Collections

Arrays, ArrayLists, and the algorithms that walk them.

Why you cannot paste here

Pasting code from a website or a friend is refused. Copying and moving code you typed yourself works normally — rename a variable, pull a loop into a method, restructure whatever you like.

The point is not to catch anyone out. It is that the typing is where the learning happens, and the exam is handwritten.

Ready when you are.

Fifty Unit 1 labs, free and open. Nothing to sign up for.

Start practising
Built by Azaharul Islam