Beginners Guide
17 items
Core Language
5 items
Collections
Java Collections guide: List, Set, Map deep dive, immutable collections, concurrent data structures, and choosing the right collection.
Optionals
Java Optional guide: creation, chaining, best practices, anti-patterns, and when to use Optional vs null.
Functional Interfaces
Java functional interfaces guide: Function, Predicate, Consumer, Supplier, method references, composition, and writing custom functional interfaces.
Generics
Java Generics guide: generic classes, methods, bounded types, wildcards, PECS principle, type erasure, and common patterns.
Concurrency
1 item
Data & I/O
2 items
JSON Processing
Java JSON processing guide: Jackson ObjectMapper, annotations, custom serializers, polymorphism, Gson comparison, and common pitfalls.
Robustness
3 items
Logging
Java logging guide: SLF4J facade, Logback and Log4j2 configuration, MDC, structured logging, performance tips, and common pitfalls.
Testing
Java testing guide: JUnit 5, Mockito mocking, AssertJ fluent assertions, parameterised tests, test patterns, and what to mock vs what not to mock.
Design & Tooling
3 items
Maven
Maven guide: POM structure, dependency management, BOM imports, multi-module projects, profiles, useful plugins, and comparison with Gradle.
Modern Java Features
Guide to modern Java features: records, sealed classes, pattern matching, text blocks, var, and a version-by-version feature table from Java 11 to 21.