Comprehensive Guide to Java Backend Interview Experience and Preparation

This article is reproduced with the original author's permission; all references to "I" refer to the reader.

Interview Experience

I previously wrote an article about my 秋招 experience, which contains many interview questions for reference.

Below is a recap of my own background and the three interview rounds I attended for a JD internship in the Baidu Cloud CDN team (audio/video related, primarily Java).

First Round (2021/01/21, 5 PM)

Self‑introduction

Introduce internship project, difficulties, responsibilities

Design patterns used in the project

Synchronized lock (upgrade, downgrade, read‑write lock) and underlying principles

Operating‑system thread synchronization mechanisms

Difference between syn and lock

Thread pool parameters and configuration for I/O‑bound vs. CPU‑bound tasks

JVM memory regions

How to troubleshoot online OOM issues

Class loading mechanism

Parent‑delegation model and how Tomcat breaks it

Write code: reverse a linked list, implement quick sort, discuss time complexities of sorting algorithms

Books read (e.g., "Deep Understanding of the Java Virtual Machine") and key takeaways

Q&A (approximately 47 minutes)

Second Round (2020/01/22, 11 AM)

Self‑introduction

Introduce JD internship project

Usage of distributed lock (Redlock) and handling master node failure

Data skew issues, consistent hashing with virtual nodes, data sharding

Cache penetration, breakdown, and avalanche

Redis Sentinel and Cluster

Underlying structure of zset : compressed list, skip‑list complexity O(log n)

Micro‑service architecture and distributed concepts

Inter‑service communication using JSF (JD's internal RPC, similar to Dubbo)

CAP theorem

Distributed transaction solutions and their pros/cons

Coding exercises (easy level, about 50 minutes)

Third Round (2020/01/22, 8:30 PM)

Self‑introduction

Implement a queue using two stacks

Non‑technical discussion: personal goals, offer expectations

General conversation (about 1 hour 15 minutes)

After the interviews, HR contacted me via WeChat, asked me to complete an online test, and later sent the offer.

Fundamentals

Key knowledge areas include basic data structures and algorithms; core Java concepts such as JVM, collections, and frameworks; operating systems and networking; and common middleware like Netty, Nginx, Redis, and MySQL.

Capabilities

Demonstrate technical strength through internship projects, clean code, design‑pattern application, and the ability to quickly understand business requirements.

Career Planning

Employers value candidates who can articulate clear short‑ and long‑term goals, whether pursuing a technical track (e.g., becoming an architect) or a management track (e.g., leading a team).

Technical Roadmap

Three years: solid technical foundation; five years: become an architect; seven years: senior architect; ten years: technical director.

Management Roadmap

Three years: handle daily development issues; five years: achieve an ideal technical level; seven years: lead a small team; ten years: lead a department.

Interview Tips

Leverage strengths and downplay weaknesses during self‑introduction.

Guide the interview toward topics you are comfortable with.

Answer questions honestly; avoid fabricating knowledge.

Show enthusiasm and a problem‑solving mindset, even when faced with uncertain questions.

Remember that interviews are a two‑way selection process.

Avoid listing generic projects like “秒杀系统” or “商城系统” without depth.

Maintain confidence regardless of academic background.

For hands‑on practice, consider building projects such as a simplified Dubbo, Netty, Tomcat, or an IoC container to demonstrate end‑to‑end understanding.

All content above is manually typed and reflects the author's personal perspective; readers are encouraged to adapt the advice to their own situations.

Recommended Reading:

Nginx default configuration that almost ruined my career

A space character caused a "disaster"

Top 10 most counter‑intuitive features of Java