Preface
Some time ago, some friends interviewed BAMT and integrated the interview questions. I have sorted out some high-frequency test questions frequently asked in Java back-end development interviews and made a PDF document (a total of 398 high-frequency questions), and also compiled some pictures The analysis and notes of the text are shared here for free today. I hope that everyone will do a good review during the interview. The long-term accumulation and short-term assault will enable you to find a satisfactory job!
Before the interview, many people may have never worked in an Internet company or have worked in a relatively short period of time. I don't know what questions will be asked in an Internet company technical interview? In addition, I may not be fully prepared. I was overwhelmed by a few questions by the interviewer within a few rounds of the interview, and ended in a disastrous defeat. I have compiled a detailed interview knowledge points for such developers, and share the high-frequency interview questions of Java interviews summarized here (including Java collections, JVM, concurrency and multithreading, Spring, MyBaits, microservices, Dubbo, Kakfa , Middleware, Redis, database, design patterns, etc.), organized and shared with everyone for free. I hope everyone can bring these questions and answers to analyze, so that you can learn targeted and perform interviews. Know thyself, ever-victorious.
Java back-end high-frequency test questions-basic part
Java collection
The hashmap, linked list, collection class, string class, object-oriented features and class loading mechanism in Java. These will be summarized in interview books, so I won't repeat them.
JVM (Java Virtual Machine)
As a Java practitioner, when looking for a job, you will definitely be asked about JVM-related knowledge. The mastery of JVM knowledge is an important criterion for candidates' technical depth in the eyes of many interviewers. Here will sort out the common JVM interview questions in detail, and give standard answers.
The internet
Familiar with common network protocols, tcp/ip protocol, http protocol, etc. Some knowledge points that are often asked in interviews, such as OSI network architecture, should be looked at in a targeted manner.
database
Generally speaking, at least one relational database must be mastered, whether it is Oracle or MySQL. Master the four paradigms of database design, things, isolation levels, and commonly used SQL statements. It is best to master another kind of k/v database, such as Redis, MySQL and Redis are relatively easy to get started, just play around with the tutorial and you will be enough.
Data structure algorithm
You can try to implement linked lists, stacks, queues, binary trees, graphs and other structures yourself. General interview books basically have explanations, so you can take a good look. In addition, the book "Sword Finger Offer" is recommended to read. Many written interview questions come from this book. It is best to type the code several times against the book yourself.
Java back-end high-frequency test points-back-end technology system
Framework part (Spring, MyBatis, SpringMVC)
For development students, the Spring framework is familiar and unfamiliar. Familiar: The knowledge points of using Spring all the time in the development process; Unfamiliar: the basic theoretical knowledge is neglected and memorized. As a result, many students know their answers to Spring-related questions during interviews, but the expressions are not complete and accurate.
Microservices (Spring Boot, Spring Cloud, Dubbo)
Redis cache
A relational database like MySQL certainly cannot meet such high concurrent requests because of slow read and write speeds and low throughput. At this time, it is necessary to choose Redis, a fast, high throughput memory database. Then comes a series of principles of Redis
Load balancing
Generally speaking, a 4C8G server can generally handle hundreds to thousands of QPS requests. A QPS of 20w/s requires at least hundreds of machines to withstand such a large magnitude. So the problem is that for a user operation, the client will send a request, and the server has hundreds of servers, so which server is the request to be handled? How to ensure that the server load is basically the same? It involves some technical points of load balancing.
message queue
The client's request will be forwarded to the back-end server A for processing after the load balancing server, and the back-end server A may need to share the data with N back-end servers for consumption. At this time, A will send a message to the message queue. These N back-end servers consume this message queue to obtain data. The following knowledge points are involved here: 1. What are the commonly used message queue middleware? (RabbitMQ, RocketMQ, ActiveMQ, Kafka, ZeroMQ, MetaMq, etc., just choose an in-depth introduction) 2. Message queue usage scenarios 3. Message queue two modes
distributed
Since client requests are distributed to hundreds of servers for processing, and each server has its own behavior, a series of distributed issues are involved here: 1. What is a distributed transaction? How to ensure data consistency? 2. Have you understood the Paxos protocol and Raft protocol? Have you understood CAP and BASE theory? 3. How to implement distributed locks? (Distributed locks can be realized based on database, zookeeper, and Redis, and there are many ways to realize it, just answer one or two.)
High concurrency
Java concurrency issues have always been one of the focuses of interviews with major companies. However, I found that many candidates often expressed confusion about various concurrency principles during interviews, as if they knew some but didn't know it clearly, which eventually led to the interview failure.
Summary of interview experience
Generally speaking, it can be divided into two parts: basic knowledge and technology used in large-scale website architecture.
- Basic knowledge
- The investigation of basic knowledge is an essential part of every company interview. The foundation is the knowledge that a position must be familiar and proficient in, including the basic grammar of programming language, data structure, JVM, algorithm, operating system, computer network, database, etc.
- Back-end technology system The back-end technology system mentioned here can be understood as a series of high concurrency and distributed processing technologies derived from the processing of massive users. Including technologies such as load balancing, message queues, high availability, data consistency, distributed transactions, or middleware based on these technologies.
In general, whether the foundation is solid determines whether or not to pass the first round of interviews, mainly to examine whether the interviewer's basic skills are solid. As long as you pass the first round of interviews, you can say that you have succeeded at least more than half. The technology in the back-end technical system determines the interview rating of the interviewer or the success or failure of the second and third rounds of interviews.
Readers share and encourage each other
If it is very close to the time of the interview, the return on investment of reading books will be lower at this time. The simplest and rude way is to directly brush the face and interview questions. Of course, the usual accumulation is indispensable! The PDF documents of the Java back-end interview high-frequency test sites mentioned above are free to share. Friends in need can help forward and follow them, and reply me with a private message in the background [Interview] to get the information for free!
Below are some of the Java study notes and back-end technology points I have compiled. It will be of great help to friends who need long-term accumulation!
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