☕ Java Knowledge Base
A structured guide covering Java from core language foundations to JVM internals and modern features, with interview-oriented guidance.
Topics Covered
| # | Topic | Description |
|---|---|---|
| 1 | Java Fundamentals | Syntax, types, control flow, and core APIs |
| 2 | Object-Oriented Programming | Classes, inheritance, polymorphism, encapsulation |
| 3 | Collections Framework | Lists, sets, maps, iteration, complexity trade-offs |
| 4 | Concurrency | Threads, executors, locks, memory model, async patterns |
| 5 | JVM Internals | Class loading, memory areas, GC, JIT, tuning basics |
| 6 | I/O and NIO | Streams, channels, buffers, file operations |
| 7 | Modern Java Features | Lambdas, streams, records, sealed types, recent updates |
| 8 | Interview Questions | Practical Q&A across core and advanced topics |
Backend Engineering Tip
Use this section as the foundation before diving into Spring, Kafka, and system design topics.
Advanced Editorial Pass: Java as a Production Engineering Platform
Senior Engineering Focus
- Connect language-level features with runtime behavior and operational impact.
- Balance readability, correctness, and performance in API and service code.
- Treat concurrency and memory behavior as design concerns, not implementation details.
Failure Modes to Anticipate
- Overusing abstractions without understanding allocation and execution cost.
- Concurrency fixes that hide race conditions instead of removing them.
- JVM tuning without workload-level evidence.
Practical Heuristics
- Start with correct, clear code, then optimize with measured evidence.
- Validate concurrency assumptions with stress tests and production-like load.
- Document JVM defaults, overrides, and the reason for each tuning change.