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Hand-written tutorials, ordered as a recommended learning path.

1. 21 Multithreading Understand threads, the Java memory model, synchronization, locks, and concurrent collections. A practical guide to writing correct multithreaded Java code. 4 min read →
2. 22 Java Optional Use Java's Optional type correctly: when to return it, when to avoid it, and how to chain operations safely without ever calling get(). 3 min read →
3. 23 Records vs Lombok Records and Lombok both reduce boilerplate, but they solve overlapping problems in very different ways. Here is when to pick which, with concrete tradeoffs. 5 min read →
4. 24 Spring Data JPA Learn Spring Data JPA from the ground up. Understand repositories, derived queries, JPQL, pagination, and transaction boundaries in real Java apps. 4 min read →
5. 25 Spring Security A practical introduction to Spring Security. Understand the filter chain, configure authentication, set up authorization rules, and avoid common mistakes. 4 min read →
6. 26 Collectors Master java.util.stream.Collectors with practical examples covering grouping, partitioning, downstream collectors, and building your own custom collector. 4 min read →
7. 27 Java Streams A practical tour of the Java Streams API: how it works, when to use it, lazy evaluation, collectors, parallel streams, and the pitfalls that trip up newcomers. 4 min read →
8. 28 Spring DI How Spring Boot wires your beans: component scanning, constructor injection, qualifiers, profiles, and the testing strategies that follow from each choice. 4 min read →
9. 29 MVC vs WebFlux Compare Spring's two web stacks: thread-per-request Spring MVC versus reactive non-blocking WebFlux, and how to choose between them. 3 min read →
10. 30 Classes Design Java classes that hold state and behavior cleanly. Constructors, encapsulation, static vs instance, records, and the equals plus hashCode contract. 5 min read →
11. 31 Collections Pick the right Java collection by performance and semantics. ArrayList vs LinkedList, HashMap vs TreeMap, immutability, and iteration without surprises. 5 min read →
12. 32 Control Flow Every branching and looping construct in modern Java, including switch expressions and pattern matching, with examples that mirror real code. 5 min read →
13. 33 Inheritance Use extends, super, and method overriding without painting yourself into a corner. When to inherit, when to compose, and how sealed types help. 5 min read →
14. 34 Install Java Install a modern JDK, verify the toolchain, and ship your first Java program from the command line without an IDE doing the magic for you. 4 min read →
15. 35 Interfaces Choose between interfaces and abstract classes with confidence. Default methods, sealed interfaces, functional interfaces, and concrete decision rules. 5 min read →
16. 36 Streams Transform collections with lambdas and the Stream API. Map, filter, reduce, collectors, parallel streams, and the pitfalls of lazy pipelines. 5 min read →
17. 37 Variables Master Java primitives, reference types, literals, and casting. Know exactly what each type costs and where overflow and precision will bite you. 5 min read →