03 — Interview Question Bank

Part of: docs/00-INDEX.md

~1,500 senior-depth questions — Short / Detailed / Example + Rapid-Fire.
Emphasis: internals, trade-offs, gotchas.

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Topic index (read in this order for systematic prep)

#	File	Topic	~Qs	Status
01	Core Java	Language fundamentals, primitives	226+	✅
02	OOP & SOLID	Design principles, composition	95+	✅
03	Collections	HashMap, ConcurrentHashMap	120+	✅
04	Concurrency	Threads, JMM, virtual threads	150+	✅
05	JVM	Class loading, GC, JIT	120+	✅
06	Streams	Lambdas, Stream API	100+	✅
07	Exceptions	Checked/unchecked, design	77+	✅
08	Generics	Erasure, wildcards, PECS	60+	✅
09	Strings & Performance	String internals, tuning	82+	✅
10	Java 9–21	Records, modules, vthreads	95+	✅
11	I/O & Serialization	NIO, JSON, Protobuf	82+	✅
12	Reflection	Reflection, annotations	72+	✅
13	Design Patterns	GoF 23 patterns	80+	✅
14	Effective Java	Best practices idioms	82+	✅
15	Spring Boot	DI, MVC, Security, Data	92+	✅
16	JDBC / JPA	Hibernate, transactions	82+	✅
17	Print Puzzles	"What does this print?"	35	✅
18	System Design	Microservices, scale	82+	✅
19	Performance	JMH, profiling, GC tune	64+	✅

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Study plan by interview stage

Stage	Topics
Phone screen	01, 03, 17 (puzzles)
Mid-level	+ 04, 05, 06, 07
Senior	+ 02, 13, 14, 18
Backend	+ 15, 16, 11

Learn tutorials first → 02-learn/37-InterviewPrep.md
Strategy → 06-career/02-InterviewGuide.md