This article first reviews the autumn recruitment road in the form of a calendar, so that you can refer to the processing progress of a certain factory; then summarizes the spring and autumn recruitment Java interview question bank; finally, make a summary and prospects, and start a new journey~
Interview experience
Jingdong interview questions
Interview experience sharing
1. Interview experience
The winter of 2018 was particularly cold, and it was undoubtedly a cold winter for programmers. I was also one of the layoffs at the end of the year. (The entire business line was cut and uncomfortable~) But it’s not good to go home when I lose my job at the end of the year. I voted for several resumes, including one from Jingdong, Jingdong Java Post.
**Job description:** 1. Participate in the design and reconstruction of the underlying architecture of the JD Finance and Insurance core business system; 2. Continue to optimize system performance in high concurrency scenarios; 3. Interface and joint debugging with insurance companies; 4. Insurance products Intelligent recommendation system development; 5. Docking with financial process related systems. **Job requirements:** 1. Bachelor degree or above in computer related majors, strong logical thinking ability, strong sense of responsibility and initiative; more than 2, 3 years of J2EE development experience, Internet development experience, solid JAVA foundation, and proficiency Use design patterns; 3. Familiar with common frameworks such as Spring, Struts2, Ibatis, and understand mechanisms; 4. Familiar with distributed development, familiar with common SOA frameworks, multi-threading, network programming, etc.; 5. Familiar with common databases and optimization, familiar with common caches , NoSql technology; 6. Familiar with Zookeeper, MQ and other components; 7. Experience in system development and optimization with high concurrency and large data volume is preferred; 8. Experience in Internet finance, especially insurance business development is preferred.
2. Jingdong interview questions (see the answer at the end of the article)
One side (mainly basic side)
I introduced myself, mainly asking what I did and what I was good at
@Autowired implementation principle
What is the default scope of Bean? Other scope of action?
What is the function of the index?
What are the main index structures in MySQL? Compare hash index and B+ tree index?
Talk about the principle of Java thread pool? What are the thread pools? What are the thread pool types of the thread pool factory and what are the thread pool parameters?
Hashmap principle, which method is used to deal with hash conflicts?
What is the difference and connection between BIO, NIO, and AIO?
Jvm memory model jmm knows all about
Talk about the Java GC mechanism?
How does Java perform garbage collection? Who will enter the old age?
What are the garbage collection algorithms? Why does the new generation use replication algorithms?
Time complexity of HashMap? How to resolve the Hash conflict in HashMap? What has changed in HashMap in Java 8?
Red-black trees need to be compared in size to be inserted. On what basis are they compared? Other Hash conflict resolution methods?
The difference between hash and B+ tree? What scenarios are they applied to? Which is better?
Two sides (database asks more)
Self introduction
Why is MyISAM query performance good?
Talk about transaction characteristics (ACID)?
What are the advantages of mysql database default storage engine
MySQL's transaction isolation level, what problems are solved respectively.
What are the common optimization steps for SQL slow queries?
Talk about optimistic locking, pessimistic locking (select for update), and write SQL implementation?
Talk about the three-way handshake and four-way wave of TCP protocol?
Which rpc frameworks have you used?
The life cycle of Java web filters?
Three sides (comprehensive side mainly distributed and cached)
Introduce yourself and talk about the project!
What is the mechanism of locking?
The design ideas and order of the database horizontal segmentation and vertical segmentation
How does Redis resolve key conflicts?
How to ensure that the database is consistent with the redis cache
How is the message queue used in the project? What specific business scenarios are used?
Which JVM-related analysis tools have you used? Are there specific performance tuning steps?
How to do MySQL slow sql optimization in general? Besides, what other methods are there to optimize?
Online server monitoring indicators, which indicators do you think need the most attention? why?
What is the difference between soa and microservices?
What technical adjustments will be involved in the evolution of a single-machine system into a distributed system? Please describe in detail from the front load to the back end.
Design a spike system?
I have sorted out the answers to the real interview questions and come back together. Because the length of the article is too long, friends who need it can join the QQ group: 935692859 to receive information for free!
3. Interview experience summary and learning route sharing:
Summary of interview experience:
Arrive as early as possible for the interview. If you can interview earlier, the interviewer is more willing to pass you (just like the voice of China, it turns around like crazy at first).
Mobilize your humorous cells during the interview and try to make the interview atmosphere a little more pleasant, so that the interviewer will remember you more deeply.
When you say your own strengths, you must supplement it with evidence, otherwise the interviewer will just be whispering
Don’t forcefully answer questions that don’t. Be careful of pitfalls. You can say something like: “I’m sorry I don’t know this question, but if I design it, I will...”
The interview is actually a two-way choice. The interviewer is evaluating your performance. At the same time, since the interviewer also represents the company, his quality and questions are also aspects you should evaluate, so don't be nervous.
Use the curtain to go through the knowledge you have summarized before each interview. I wrote notes of tens of thousands of words on the screen, and I took it out every interview, so I can basically answer the basics of the interview.
Learning route:
Most professions need a growth system to make people have aspirations. The architect is an important node that often appears in the growth of the programmer group. Every good architect is an excellent programmer. However, it is not easy for a good programmer to advance to an architect.
For programmers with a certain amount of background R&D experience (especially more than 5 years of experience), the desire to become an architect is stronger, so they will spend more time learning and improving their architectural skills, but they are often faced with constraints due to objective conditions There are many difficulties: you can't get in touch with the first-line actual architecture technology, especially the technical depth and difficulty architecture technology. Do not know the specific background of the core technology point? At the same time, there is an urgent need to master: the industry’s current mainstream dry goods technology + cutting-edge technology, Internet core technology hard skills + core soft skills, master the essence of architecture technology, know what it is, know it better, build the foundation of the architecture, go deep into the core, and hit the fault directly , Refused to be trapped.
So you need a clear learning route-this is a typical programmer's growth process:
Use Java---->In-depth understanding of Java to accumulate experience---->Independent design and analysis ability---->Universal hand!
Therefore, you must learn:
One, open source framework analysis (each
Programmers deal with code every day. After several years of basic education and vocational training, most programmers can "write" code, or at least copy and modify code. However, there are not many who can read the code, and few can read the code and really understand the source code of some large projects. This also caused a lot of wrong way to look at the source code.
How to analyze the source code correctly? Our goal should be on the most commonly used frameworks:
Second, the architect builds the foundation
From architecture design to application layer tuning, and then in-depth understanding of the underlying principles, a solid Java basic skills can turn oneself into a sweeping monk: memory model, concurrency mode, thread model, lock details, etc.
Three, high-performance architecture
We not only plan for the project, but also solve all performance problems. Only in-depth study of the underlying principles of JVM, Mysql underlying optimization and Tomcat tuning can achieve the effect of knowing what it is and why. In addition to performance optimization, it can also provide general common ideas and consideration points for program selection to help you develop awareness, thinking, and the ability to make various trade-offs when selecting programs.
Four, microservice architecture
About the choice of microservice architecture
In the right project and the right team, the benefits of adopting the microservice architecture will exceed the cost. Microservices architecture has many attractive places, but before embracing microservices, we also need to recognize the challenges it brings. Need to avoid "microservices" for the sake of "microservices". Microservice architecture introduction strategy-For traditional enterprises, at the beginning, you can consider introducing some appropriate microservice architecture principles to transform existing systems or build new microservice applications, gradually explore and accumulate experience in microservice architecture, rather than fully implement microservice architecture. Service architecture.
Five, teamwork
Development tool engineering
A software project management tool that manages project construction, reports and documentation through a short paragraph of description information. The programmer’s battle is often not a person’s battle. How can we efficiently remove duplication, perform code reviews, adjust functions, and debug under a single platform, so that we can proceed step by step in a unified planning and chaotic code stacking process Find your own record. All this depends on effective tools.
Six, B2C project actual combat
Project actual combat
If you want to base yourself in an Internet company and not be submerged in the Internet wave, you need to practice project development and actual combat. It is also a measure of your own ability. How much is equal to how much you get in return. A seemingly simple project demand map, how much can you know about the underlying principles and implementation principles? How much knowledge do you need to build a complete B2C project platform? All of this needs our consideration.
After reading the learning routes I shared, do you feel that your skills need to be strengthened, and your thinking should not just stay on the surface?
Of course, I also prepared an advanced architecture video material and the above high-definition mind map for students who want to improve their skills.
Information acquisition method: click here, password: CSDN , thank you, everyone is welcome to pay attention to forwarding and collection.