Learn Java

Why learn Java?

Java runs on billions of devices worldwide and is the backbone of enterprise software, Android apps, and large-scale distributed systems. Companies like Amazon, LinkedIn, Google, and major banks use Java for mission-critical applications. Java's strong type system and vast ecosystem make it one of the most in-demand languages in the job market.

What you'll learn in this Java tutorial

This free, interactive Java course covers variables, data types, control flow, loops, functions, classes, objects, inheritance, interfaces, collections, error handling, JSON processing, and concurrency — all by compiling and running real Java code in your browser.

22 topics · 144 hands-on lessons · all levels

Java tutorial topics

1. 1Getting StartedWrite your first Java program — understand the boilerplate, System.out.println, … · 8 lessons · 15 min
2. 2VariablesDeclare variables in Java — types, assignment, naming rules, var, and the differ… · 8 lessons · 18 min
3. 3Data Types & CastingJava's 8 primitive types, the String class, type casting, autoboxing, and wrappe… · 8 lessons · 20 min
4. 4Strings & StringBuilderMaster Java String methods, String.format, StringBuilder for efficient building,… · 8 lessons · 20 min
5. 5Operators & Control FlowComparison operators, logical operators, if/else, switch expressions, and the te… · 7 lessons · 18 min
6. 6Loopsfor, while, do-while, enhanced for-each, break, continue, and labeled loops — co… · 8 lessons · 18 min
7. 7ArraysJava arrays — declaration, initialisation, traversal, multi-dimensional arrays, … · 7 lessons · 18 min
8. 8MethodsDefine and call methods, parameters, return types, method overloading, varargs, … · 7 lessons · 20 min
9. 9Classes & ObjectsCreate classes, constructors, instance fields, methods, this keyword, and the di… · 6 lessons · 22 min
10. 10EncapsulationAccess modifiers, private fields, getters and setters, data validation, and why … · 6 lessons · 18 min
11. 11InheritanceExtend classes with extends, use super, override methods, understand the Object … · 6 lessons · 20 min
12. 12InterfacesDefine interfaces, implement multiple interfaces, default methods, functional in… · 6 lessons · 20 min
13. 13PolymorphismMethod overriding, dynamic dispatch, upcasting and downcasting, and how polymorp… · 5 lessons · 18 min
14. 14GenericsWrite type-safe reusable code with generics — generic classes, methods, bounded … · 5 lessons · 20 min
15. 15Error Handlingtry/catch/finally, checked vs unchecked exceptions, custom exception classes, mu… · 6 lessons · 18 min
16. 16CollectionsArrayList, LinkedList, HashMap, HashSet, TreeMap, Queue, Stack, and the Collecti… · 7 lessons · 22 min
17. 17Lambdas & StreamsLambda expressions, method references, and the Stream API — filter, map, reduce,… · 7 lessons · 22 min
18. 18Packages & ImportsOrganise code with packages, import statements, access modifiers in the context … · 6 lessons · 15 min
19. 19File I/ORead and write files using java.nio.file.Files, Path, BufferedReader/Writer, and… · 5 lessons · 18 min
20. 20ConcurrencyThreads, Runnable, ExecutorService, synchronized, volatile, Future, and Completa… · 6 lessons · 25 min
21. 21HTTP & JSONMake HTTP requests with Java's built-in HttpClient, parse JSON responses, build … · 6 lessons · 22 min
22. 22Modern JavaRecords, sealed classes, pattern matching, text blocks, var, switch expressions,… · 6 lessons · 20 min

Who is this Java course for?

Beginners who want a rock-solid language for career development, Android developers, enterprise engineers, and anyone preparing for Java coding interviews.