Your Journey at a Glance
💡 How to use this roadmap
Work through each phase in order. Click on a skill to expand it — you'll find a description and curated resources. Don't rush; understanding beats speed. Complete one phase before moving to the next.
Foundations
Get your environment ready, understand what Java is and where it runs. Write your first programs and build confidence with basic syntax.
Core Java
The bread and butter of production Java. Everything you write in the real world rests on these pillars — OOP, Collections, Exceptions, and I/O.
Advanced Java
Level up from writing code that works to code that scales. Concurrency, JVM internals, the Stream API, and modern Java features that every senior engineer must own.
Ecosystem & Tooling
Real projects need more than the language. Build systems, testing, logging, database access, and design patterns are what separate hobby code from professional software.
Expert & Production
The final frontier — writing Java that performs at scale, survives production, and evolves safely. Deep technical mastery meets real-world engineering judgment.
Roadmap Complete!
You now have the foundations of a production-ready Java engineer. Apply by building real projects.
Online Ticket Booking System
A full-featured event ticket booking system built entirely in pure Java. Exposes an HTTP API via Java's built-in HttpServer, persists data to MySQL using raw JDBC, handles concurrent seat reservations with ReentrantLock, and ships a suite of JUnit 5 + Mockito tests — demonstrating every concept from the roadmap without a single framework.
What you'll build
- HTTP API (no framework): BookingHandler, EventHandler, UserHandler using com.sun.net.httpserver.HttpServer
- MySQL persistence via raw JDBC — PreparedStatement, ResultSet, manual transaction management
- HikariCP connection pool configured programmatically (no Spring context)
- Concurrent seat locking: ReentrantLock per event prevents double-booking under load
- ExecutorService-based bulk event import from CSV using CountDownLatch for completion sync
- Generics-based Page<T> and Result<T> wrappers for all API and service responses
- Java Stream API + Optional: revenue reports, occupancy rates, and overdue payment detection
- JUnit 5 + Mockito test suite: unit tests per layer, integration tests against a real MySQL test database
Tech stack
Key highlights
- ✦Zero Spring, zero ORM — every dependency is wired manually to internalise DI and layering
- ✦ReentrantLock ensures thread-safe seat reservation across concurrent HTTP requests
- ✦Tests cover >80% of business logic including concurrency edge cases and JDBC rollback paths
Key Resources for Java
Handpicked books, websites, and YouTube channels to go alongside this roadmap.
- Effective Java, 3rd Ed.Joshua Bloch — the definitive Java best-practices bible
- Java Concurrency in PracticeBrian Goetz — still the authoritative guide to Java concurrency
- Head First Java, 3rd Ed.Kathy Sierra & Bert Bates — best intro for visual learners
- Java: The Complete Reference, 13th Ed.Herbert Schildt — comprehensive desk reference