Java Tutorial

Java is a strongly typed, object-oriented general-purpose language used widely for backends, Android, big data, and enterprise systems. This track uses JDK 21 (LTS) and IntelliJ IDEA, from syntax and OOP through Spring Boot (JPA / validation / Security), concurrency, and a Docker deploy intro.

Learning path

Environment

1. Java Intro
2. Install JDK
3. IntelliJ IDEA
4. First Program

Basic syntax

5. Comments
6. Variables & Constants
7. Data Types
8. Operators

Control flow

9. if / else
10. switch
11. for Loop
12. while Loop
13. break / continue

Object-oriented basics

14. Arrays
15. Methods
16. Classes & Objects
17. Constructors
18. Encapsulation
19. Inheritance
20. Polymorphism

Core advanced

21. Collections
22. Exceptions

OOP advanced

23. Abstract Classes
24. Interfaces (advanced)
25. record

Generics & Stream

26. Generics (advanced)
27. Stream

Build & backend

28. Maven
29. Gradle
30. Spring Boot Intro
31. First Web API
32. Spring Data JPA
33. Validation
34. Global Exception Handling
35. Spring Security Intro

Concurrency & deploy

36. Concurrency Basics
37. Docker Basics
38. Summary

What you need beforehand

Item	Notes
JDK	Required; this tutorial recommends 21 LTS
IDE	Prefer IntelliJ IDEA Community; Ultimate is nicer for Spring but not required
OS	Windows / macOS / Linux all work
Docker	Only needed for the Docker lesson; install later if you want

TIP

Java cannot run in this site’s playground. Create a project in IDEA, paste the samples, and run them locally. Spring / Docker chapters need network access for dependencies or images.

Next: Java Intro