Java
Cheatsheet and Decision Guide
Practical quick reference: collection decision trees, complexity tables, copy-paste code patterns, top 20 mistakes to avoid, and 50 interview questions.
Java
Performance Pitfalls
Real-world performance: why Big-O hides constant factors, actual memory footprints, JMH benchmarking, JFR/JMC monitoring, and collection-specific antipatterns.
Java
Testing and Debugging Collections
Build comprehensive collection test suites with AssertJ/Hamcrest, debug ConcurrentModificationException, diagnose memory leaks, and test thread-safety.
Java
JPA, Jackson, and Spring Integration
Navigate enterprise framework complexities: JPA collection mappings, LazyInitializationException prevention, Jackson serialization, and Spring injection patterns.
Java
Views, Wrappers, and Defensive Copies
Distinguish views (subList, keySet, entrySet) from copies, synchronized wrappers with limitations, checked wrappers for type safety, and defensive API patterns.
Java
Streams and Collectors
Master Stream API transformations, Collectors for complex aggregations, toMap()/groupingBy() pitfalls, and when parallel streams help versus hurt performance.
Java
Java 21 Sequenced Collections
Modern Java 21 evolution: SequencedCollection/Set/Map for consistent first/last operations, reversed() views, and Virtual Thread implications for blocking collections.
Java
Immutable Collections
Evolution from Collections.unmodifiableXxx() to Java 9+ List.of()/Set.of()/Map.of() factories, structural vs deep immutability, and null handling differences.
Java
Blocking Queues
Foundation of concurrent applications: BlockingQueue family, producer-consumer patterns, backpressure handling, and thread pool internal mechanisms.
Java
Copy-on-Write Collections
Understand copy-on-write semantics for read-heavy concurrent scenarios, snapshot iterators preventing ConcurrentModificationException, and event listener patterns.
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