Software architecture principles for maintainable, testable, decoupled systems.
Java collections: computeIfAbsent, getOrDefault, removeIf, immutables, and Comparator chains that eliminate entire bug categories.
Stop fighting java.util.Date. Master LocalDateTime, ZonedDateTime, Instant, and Duration — predictable, thread-safe time handling.
Java singletons: enum patterns, double-checked locking, and holder-classes — and when dependency injection is the better answer.
SOLID beyond theory: real production anti-patterns, Spring Boot refactorings, and the design constraints that prevent codebase rot.
Go error handling: sentinel errors, wrapping, errors.Is/As, custom types, and production patterns that prevent silent failures.
Java streams: pipeline internals, where streams beat loops, parallel stream traps, and when to use collectors vs teeing.
Handler, service, and repository layers. Custom error types. Middleware chains. Health probes. The patterns for Go APIs handling millions of requests.