Introduction

Why Java?

Java is one of the most widely used programming languages in the world. It powers Android apps, enterprise backends, financial systems, and large-scale distributed services. The JVM (Java Virtual Machine) makes it truly portable: write once, run anywhere.

  • Statically typed — types are checked at compile time, catching entire classes of bugs before they reach production.
  • Object-oriented — everything is a class. Java's OOP model (classes, interfaces, inheritance, generics) scales from small programs to massive systems.
  • Mature ecosystem — Spring, Maven, Gradle, JUnit, and thousands of battle-tested libraries.
  • Performance — the JVM's JIT compiler makes Java competitive with compiled languages for server workloads.

What You Will Learn

This course has 15 lessons organized into 5 chapters:

  1. Basics — Hello World, variables, strings, and arrays.
  2. Control Flow — Conditionals and loops.
  3. Methods — Static methods and recursion.
  4. Object-Oriented Programming — Classes, inheritance, interfaces, and abstract classes.
  5. Collections & Generics — Generics, ArrayList, and HashMap.

All code runs in-browser via TeaVM — a Java-to-WebAssembly compiler — so there's nothing to install.

Next →