preface
Autumn recruitment ended, the reserve three silver four interview, 2020 said that the job is not easy to find, but also the requirements of developers become higher.
Recently, some friends interview BAMT back integration of this problem, they have compiled some Java back-end development interview of high frequency examination questions often asked to make a PDF document (a total of 398 high frequency problem), also organize some graphic analytic and notes at the same time, today in this free share for you, I hope you in the upcoming October interview review, Long-term accumulation and short-term assault so that they can find a satisfactory job!
Many of you may not have worked in an Internet company or have worked in an Internet company for a short time before the interview, so you don’t know what kind of questions will be asked in the technical interview of an Internet company? In addition, they may not be fully prepared for the interview. After a few rounds, they will be confused by the interviewer’s questions and finally end up in a fiasco. Java collection, JVM, concurrency and multithreading, Spring, MyBaits, microservices, Dubbo, Kakfa, middleware, Redis, database, design patterns, etc. Sorted out, free to share with you, I hope you can take these questions and answers to analyze, can let you carry out targeted learning, to do the interview to know yourself and your enemy, win every battle.
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Java backend high frequency test point problems – The basics
Java collection
Java inside hashMap, linked list, collection class, String class, object-oriented features and class loading mechanism, etc. All of these will be summarized in the interview books and will not be repeated.
JVM (Java Virtual Machine)
As a Java practitioner, you will inevitably be asked about JVM knowledge when looking for a job. Knowledge of the JVM is seen by many interviewers as an important measure of a candidate’s technical depth. Common JVM interview questions will be sorted out in detail and given standard answers.
network
Familiar with common network protocols, such as TCP/IP and HTTP. Topics that are often asked about in interviews, such as OSI network architecture, should be looked at specifically.
The database
In general, you should know at least one relational database, whether it’s Oracle or MySQL. Master database design patterns, objects, isolation levels and common SQL statements. It is best to master a K/V database, such as Redis, MySQL and Redis are relatively easy to get started, to play a tutorial will play.
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Data structure algorithm
Try implementing linked lists, stacks, queues, binary trees, graphs, etc. The book of general interview kind basically has explain, can take a good look. In addition, “Sword finger Offer” this book recommended to read, many written interview questions are based on this book, it is best to type code several times in the book.
Java backend high frequency test point problem – backend technology system
Framework part (Spring, MyBatis, SpringMVC)
For developers, the Spring framework is both familiar and unfamiliar. Familiarity: Knowledge of using Spring all the time during development; Unfamiliar: Lack of arrangement and memorization of basic theoretical knowledge. As a result, many students know their answers to spring-related questions in the interview, but their expressions are not complete and accurate.
Microservices (Spring Boot, Spring Cloud, Dubbo)
Redis cache
A relational database of the MySQL type would certainly not be able to handle such high concurrency requests due to slow read/write speeds and low throughput. At this time, we must choose Redis, which is a memory database with high speed and throughput. Then comes a series of problems of Redis principle
Load balancing
Typically, a 4C8G server can handle requests of several hundred to several thousand QPS, while a 20W /s QPS requires at least hundreds of machines to withstand such a large order of magnitude. Then the problem comes, a user’s operation, the client will issue a request, the server has hundreds of servers, so which server to send this request to deal with? How do you ensure that the load on your servers is basically consistent? This involves some technical aspects of load balancing.
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The message queue
After passing the load balancing server, the client requests are forwarded to back-end server A for processing. After processing, back-end server A may share data with N back-end servers for consumption. At that point, A will send A message and write it to the message queue. These N back-end servers consume the message queue to get the data. The following points are involved: 1. Which message queue middleware are commonly used? (RabbitMQ, RocketMQ, ActiveMQ, Kafka, ZeroMQ, MetaMq, etc.) 2. Usage scenarios of message queues 3. Two modes of message queues
distributed
Since the client request is distributed to hundreds of servers to process, each server has its own behavior, which involves a series of distributed problems: 1. What are distributed transactions? How to ensure data consistency? 2. Are you familiar with Paxos and Raft? Are you familiar with CAP and BASE theory? 3. How to implement distributed lock? (Database based, ZooKeeper, Redis can implement distributed lock, there are many ways to implement, just need to answer one or two)
High concurrency
Java concurrency has always been one of the most important issues in the interview. However, I have found that many candidates are often confused about various concurrency principles during the interview, as if they know something but can’t explain it clearly, which ultimately leads to the failure of the interview.
Summary of interview experience
In general, it can be divided into two big chunks: basic knowledge and techniques for large-scale web architecture.
- Basic knowledge of
- The investigation of basic knowledge is an indispensable part of every enterprise interview. Basic is the knowledge that a job must be familiar with and master well, including basic syntax of programming language, data structure, JVM, algorithm, operating system, computer network, database and so on.
- Back-end technology system The back-end technology system can be understood as a series of highly concurrent and distributed processing technologies derived from massive user processing. Technologies such as load balancing, message queuing, high availability, data consistency, distributed transactions, or middleware based on these technologies.
In general, whether the foundation is solid or not determines whether the candidate can pass the first round of interview, mainly examining whether the interviewer’s basic skills are solid or not. If you make it through the first round of interviews, you are at least halfway there. The technology in the back-end technology system determines the candidate’s interview rating or the success or failure of the second or third round of interviews.
Readers share and encourage each other
If leave the time of interview very close, the investment return that reads a book at this time is compared can be lower, the simplest and brutal way is to brush face classics and face examination questions directly. Of course, there is no usual accumulation! Vx: Yunduoa2019 or scan the qr code below and follow the assistant’s guidance to obtain it by yourself
The following is my collation of some Java learning notes and back-end technology points learning notes map, the need for long-term accumulation of friends will be a great help!
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