Comprehensive Java Interview Questions and Topics Guide

Java Basics

A collection of core Java concepts such as primitive types, wrapper classes, object references, String handling, equals vs ==, autoboxing, constant pools, common Object methods, reference types, hashCode usage, collection interfaces, and common pitfalls.

Multithreading

Key topics include thread creation, safety, locks (spin, optimistic, pessimistic), Java Memory Model, CAS, AQS, atomic classes, Executors framework, blocking queues, Callable/Future, thread pools, synchronization primitives, lock implementations, deadlock detection, and performance considerations.

Design Patterns

Overview of classic patterns such as Singleton, Factory, Observer, Decorator, Adapter, Proxy, Template, and Strategy, with their typical use cases in Java applications.

JVM

Details on memory model partitions, object allocation, GC algorithms (reference counting, tracing, mark‑sweep, mark‑compact, copying), collector types (CMS, G1), GC phases (Minor vs Full), debugging tools (jmap, jstack, jconsole), class loading process, and delegation model.

Data Structures & Algorithms

Covers arrays, linked lists, stacks, queues, hash tables, sorting algorithms (bubble, selection, insertion, shell, merge, quick, heap, bucket, radix), binary trees, B+ trees, AVL, red‑black trees, graph traversals (BFS, DFS), MST (Prim), shortest path (Dijkstra), KMP, dynamic programming, greedy, divide‑and‑conquer, and big‑data processing techniques.

Databases

Discusses ACID properties, isolation levels, storage engines (InnoDB vs MyISAM), query execution order, optimization strategies, index types (B+ tree, hash, primary, unique), left‑most prefix rule, lock types, relational vs NoSQL differences, normalization, read/write splitting, replication, explain plan, long‑query handling, and deadlock resolution.

Spring

Explains IoC/DI concepts, BeanFactory vs ApplicationContext, bean lifecycle, AOP implementation, transaction management and propagation, design patterns used in Spring, MVC workflow, circular dependency resolution, and controller concurrency safety.

Netty

Describes BIO/NIO/AIO models, core Netty components, threading model, TCP packet framing (sticky/half packets), serialization protocols, zero‑copy techniques, and performance characteristics.

Cache

Focuses on Redis data structures, cache penetration, avalanche, distributed locks, concurrency issues, persistence options, eviction policies, clustering, sharding, and cache invalidation strategies.

Technical Frameworks

Lists open‑source frameworks examined, reasons for using Redis and Spring, Netty thread‑pool usage, Spring IOC container initialization and bean resolution mechanisms, AOP internals, and message‑queue implementation challenges.

Technical Depth

Includes transaction implementation, JDK source code insights, HTTP/TCP protocols, consistent hashing, class loading/unloading, IO vs NIO, thread‑pool internals, HTTP connection pooling, and database connection‑pool mechanics.

Distributed Systems

Covers CAP and BASE theorems, eventual consistency, consistent hashing, two‑phase commit, distributed locks and sessions, message consistency, load balancing algorithms, proxy types, CDN principles, QPS/t吞吐提升, Dubbo internals, service governance, idempotency, MQ reliability, sharding strategies, and Zookeeper usage.

System Architecture

Guidelines for building high‑availability systems, applying design patterns for scalability, high cohesion/low coupling, interface vs messaging decisions, dependency decoupling, documentation structure, system vs module boundaries, incident handling, and large‑scale feature design (e.g., whitelist queries,秒杀, ticketing).

Linux

Differences between hard and soft links, kill command behavior, common shell commands, system monitoring, pipelines, grep, find, awk, and scripting basics.

TCP/IP

OSI/TCP‑IP layer functions, TCP vs UDP, packet structures, three‑way handshake/four‑way termination, congestion control, sliding window, HTTP message format and status codes, long‑connection handling, cookies vs sessions, DNS resolution flow, ICMP ping, socket programming, IP classification, router vs switch differences, and recommended reading.

Soft Skills

Approaches to learning new technologies, staying updated, task prioritization, handling delays, resolving design disagreements, ensuring code quality, career planning, team vision, personal growth, essential backend engineer abilities, and architect responsibilities.

Recommended Reading

Links to detailed articles on multithreading interview questions, Spring interview topics, Java basics, distributed transaction solutions, microservice architecture, and large‑scale tracing systems.

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Author: Peng Lei – Source: http://www.ymq.io – © Author, please credit when reposting – Follow the "搜云库" WeChat public account for more technical content.