Java Programming Course: OOP, DSA and Backend

This Java programming course teaches the version students will actually meet: Java 25 LTS, released on 16 September 2025 with eighteen JDK Enhancement Proposals. It runs from first principles through data structures to a deployed backend service.

Why an LTS release matters for teaching

Java ships a new version every six months, but only Long-Term Support releases get years of support — and those are the versions universities and employers standardise on. Teaching the newest release would mean teaching something a student's first workplace has not adopted.

Java 25 is also a natural teaching target because two long-running language projects finished in it: pattern matching is complete, now including primitive types, and virtual threads became the default model. Both simplify what has to be taught.

Stage 1: the language and genuine OOP

Java is where object-oriented design is best learned, because the language makes the structure explicit rather than optional.

The emphasis is on design that survives change: interfaces as contracts, composition preferred over inheritance with the cases where inheritance is genuinely right, records for data carriers, and sealed types for closed hierarchies. Students learn why a deep inheritance tree is usually a mistake — by being given one to modify.

Generics come with type erasure taught honestly, including what erasure prevents, since this is a recurring source of confusion that a clear explanation removes permanently.

Collections are taught by cost. ArrayList against LinkedList, HashMap against TreeMap — each with its complexity guarantee, and each chosen by access pattern. Alongside it, equals and hashCode as a correctness problem, with a demonstration of exactly what breaks in a HashMap when they are wrong.

Stage 2: data structures and algorithms

Every structure is implemented by hand before the library version is permitted. A student who has written a hash table understands collision handling and load factor as real constraints rather than vocabulary.

Then the techniques: recursion, two pointers, sliding window, binary search on an answer, greedy reasoning with a proof, dynamic programming built from states and transitions, and graph algorithms including shortest paths and union-find.

Modern Java arrives here too — lambdas, streams and Optional, taught with judgement about when a stream is clearer than a loop and when it is merely fashionable. Pattern matching, completed in Java 25, replaces a great deal of older defensive code.

Concurrency, much simpler than it used to be

Concurrency is where Java teaching has aged worst, because the right answer changed.

Students start with threads and the memory model, enough to understand why shared mutable state is dangerous. Then virtual threads, the default model in Java 25. Because blocking IO is no longer expensive, most of the reason teams adopted reactive and callback-heavy styles has gone.

The practical consequence is that students learn the straightforward blocking style — which is also now the performant one — and meet structured concurrency for managing related tasks. This is substantially easier to teach correctly than the reactive patterns it displaces, and it is what new Java code should look like.

Stage 3: backend engineering

The final stage builds a service: layered architecture with dependency injection, a Spring Boot REST API with validation, error handling and OpenAPI documentation.

Persistence is treated as an engineering problem rather than an annotation exercise — relational modelling, SQL and indexes, JPA together with its costs, transactions and isolation levels, and migrations kept in version control.

Then operation: containers, externalised configuration and secrets, caching, logging and metrics, and reading a profile to locate the actual bottleneck rather than the suspected one.

What you build

The capstone is a tested, documented, containerised REST service backed by a real database — plus a short written note on its limits and how it would scale.

That note is assessed. A student who can state where their own service would fail under load is showing the judgement that distinguishes an engineer from someone who has completed a tutorial.

Who this suits

Students from Class 9 upward, and undergraduates aiming at backend, enterprise or Android development. Java is also a reasonable first language: the compiler catches mistakes that would otherwise ship, at the cost of more ceremony before the first working program.

Classes are online in small groups of up to eight. Students who already program in another language can skip the opening weeks after a short diagnostic.