2021 gold three silver four spring recruits BATJ big factory must, stay up late to see the real Java factory interview questions

Preface

How to successfully win an offer in gold three silver four! BATJ Dachang Mianjing (The key to success: knowing the nine core knowledge + madly brushing the real interview questions of Dachang)

First round: team interview

In the first round, your team members are basically interviewing you. It is a senior who is at the same level as you or a P who is higher than you. I basically didn’t ask anything special. I mainly talked about the projects on my resume. Here You need to be familiar with your project.

I personally think that here you have to explain clearly what your role has done and did not do in the project, and then it is best to focus on the part that you have done, and then the interviewer will pick some details from what you said. Ask you, this part differs from person to person, don't talk nonsense if you know or don't.

Finally, I will ask you some basic knowledge of TCP/UDP, network model, etc. I think on this side, as long as your project is reliable, not bragging, and solid, it shouldn't be a problem.

Second round: Supervisor interview

This side is actually similar to the first side, that is, your seniors have screened their resumes, and then come to your supervisor to interview you. On this side, my interviewer asked me to mainly introduce the resume (maybe because I am a social recruitment, they are more interested in project experience), and then I said it again, because I thought about it after I finished the interview, so this time Basically, I paid attention to the things I didn't talk about last time or I didn't talk well this time, and basically what I said was OK.

Then the next step is to focus on what you are talking about. There is really no fixed routine in this part. They will ask you "how to achieve it, why it is achieved, whether there is any interest in it. " "A better way to achieve" these three issues.

This time, in addition to being familiar with your own project, you are also required to think about what you have done. If you think about it now, it is definitely unreliable. In this round, the opponents are at least P8 level people, don't pretend to understand nonsense. Still the same sentence, knowing is knowing, not knowing is not knowing, it is knowing.

The third round: cross interview

This is basically to find a leader from another department and your future supervisor to meet you again to prevent cheating in the interview of your own department.
The basic routine is similar to the two sides, but I will ask you more about basic knowledge and programming ability, mainly for the purpose of evaluating you, and certainly not for embarrassing you, so it is enough to show yourself.

Fourth round: code interview

According to my later brothers, this aspect was originally a two-sided aspect, which I wanted to save, but it was added back to me due to process regulations later, so I went through an online written test interview. This interview is to give you an online website, and then you and your interviewer log in together, share the web page, and then he will give you questions, you can write the code on the spot, pseudo-code, and then you can tell him again Your logic is ok.

There's nothing to talk about on this side. Just write code. It's the mule that came out with a horse. The question is not difficult. I answered two questions. One is given to me for half an hour. The first one is to give you a shell command. The function of execution is probably to read a log file and then according to a certain field in the log. Sort, then take the top five and output. Probably the test site is:

1. You have to understand this shell command that has cat, awk, sort, etc., which is quite long;

2. Realize it;

3. Time and space complexity/efficiency;

4. Speak clearly.

The second question is to reverse the string, which is probably to separate the string "123456789" from the middle, and then reverse them separately, and then output, the output result is "432159876". Probably the test site is:

1. Realize it;

2. Time and space complexity/efficiency;

3. Speak clearly;

4. Try to give an optimization plan;

It is probably this type of question, which will definitely not be repeated. The brother said that it is probably the problem they encountered in writing the code recently, so he asked you directly, so there is no fixed routine, and you don’t need to brush the questions temporarily. , Just do whatever you want.

Fifth round: boss interview

By the time this side is basically stable, of course I have also seen hanging ones. On this side, your supervisor’s supervisor has come to meet you. I was still talking about the project first, and then focusing on the key questions. However, the obvious difference from the second and third sides is that he will ask you for higher-level solutions and no longer stick to it. The little thing you do will let you explain the solution of your project as a whole or partly as well as your own thinking (the three problems above), and will let you try to give a better solution. And explain why.

I personally feel that this side is more of a test of your overall view. If you have been stuck with your own small world, you will probably suffer. Of course, the interview is divided, and some non-technical supervisors just chat with you about your ideals in life. If you don’t match, you will be eliminated.

Sixth round: HRG interview

If you can meet this side, you basically get an offer 99%! The main thing is to talk to you about life, ideals, three perspectives, and salary. As long as you are not anti-human and nonsense, it's OK.

After sharing my interview experience, many friends asked me if I have any learning methods. In fact, in addition to the skills I need to master, some skills and some interview questions are also indispensable in the interview process! You can share an interview question you brushed yourself, which covers : Java basics, JVM, multithreading and high concurrency, spring, springMVC, MyBatis, SpringBoot, SpringCloud, microservices, database, network bottom, TCP, data structure and algorithms Wait a minute and a complete set of real interview questions from big factories!

Summary of nine core knowledge points of Java

There are nine parts in this note, covering a summary of interview knowledge points from Java novices to Java architects. Here is a keynote for everyone: this note is 100% free! Because there are too many knowledge points in this note, the editor can't show it all for everyone. The free way to get this note is here to get it~

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2021 gold three silver four spring recruits must-have, the real questions of big Java manufacturers that you have to see if you stay up all night

 

2021 gold three silver four spring recruits must-have, the real questions of big Java manufacturers that you have to see if you stay up all night

 

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2021 gold three silver four spring recruits must-have, the real questions of big Java manufacturers that you have to see if you stay up all night

 

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2021 gold three silver four spring recruits must-have, the real questions of big Java manufacturers that you have to see if you stay up all night

 

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Design patterns

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2021 gold three silver four spring recruits must-have, the real questions of big Java manufacturers that you have to see if you stay up all night

 

2021 gold three silver four spring recruits must-have, the real questions of big Java manufacturers that you have to see if you stay up all night

 

Summary of interview questions

2021 gold three silver four spring recruits must-have, the real questions of big Java manufacturers that you have to see if you stay up all night

 

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Dachang Interview Part of the Real Questions Show

Hangzhou-Ant Financial-Java Advanced

  1. What has changed from jdk1.7 to jdk1.8 Map (underlying)?
  2. ConcurrentHashMap
  3. What is the difference between parallel and concurrency?
  4. What happened to the java virtual machine from jdk1.7 to jdk1.8?
  5. If you were asked to design a middleware by yourself, how would you design it?
  6. What is middleware?
  7. Have you ever used ThreadLock, talk about its role?
  8. What is the difference between Hashcode() and equals() and ==?
  9. In the mysql database, under what circumstances are indexes set up but not available?
  10. Will mysql optimize, mycat sub-library, vertical sub-library, horizontal sub-library?
  11. Distributed transaction solution?
  12. Will sql statement optimization, tell me what you know?
  13. Have you understood the storage engine of mysql?
  14. Red-black tree principle?

Hangzhou-Ant Financial-Senior Engineer

Ant Java side

  1. What is the relationship between binary search tree and balanced binary tree, strong balanced binary tree (AVL tree) and weakly balanced binary tree

(Red and black tree) What is the difference

  1. The difference between B-tree and B+ tree, why MySQL uses B+ tree
  2. How does HashMap resolve Hash conflicts
  3. The difference between epoll and poll, and its application scenarios
  4. Briefly describe the principle of thread pool, what is the blocking queue used by FixedThreadPool?
  5. The difference between sychronized and ReentrantLock
  6. Sychronized's spin lock, deflection lock, lightweight lock, and heavyweight lock are introduced and contacted respectively
  7. What are the problems with HTTP, what are the encryption algorithms, the possible problems for different encryption methods, and

How does HTTPS ensure secure transmission

Ant Java Two Sides

  1. What are the major categories of design patterns, and which design patterns are familiar with
  2. The volatile keyword, how does it ensure visibility and order
  3. Java's memory structure, which parts of the heap are divided into, and how old is the default age to enter the old age
  4. How does ConcurrentHashMap ensure thread safety, and what changes have been made in jdk1.8
  5. Why does the bottom layer of ConcurrentHashMap need a red-black tree
  6. How to do MySQL optimization
  7. Talk about oom and how to deal with this situation, whether you have used log analysis tools

Ant Java Three Sides

  1. Project Introduction
  2. How do you ensure data consistency between Redis cache and database?
  3. Redis cache avalanche? breakdown? penetrate?
  4. Which messaging middleware are you familiar with, and have you done performance comparisons?

Shanghai-Pinduoduo-Java Advanced

1. Three elements of concurrent programming?

2. What are the ways to achieve visibility?

3. The value of multithreading?

4. What are the ways to create threads?

5. Comparison of the three ways of creating threads?

6. The state flow diagram of the thread

7. Java threads have five basic states

8. What is a thread pool? What are the ways to create it?

9. The creation of four thread pools:

10. What are the advantages of thread pools?

11. What are the commonly used concurrency tools?

12. The difference between CyclicBarrier and CountDownLatch

13. What is the role of synchronized?

14. The role of the volatile keyword

15. What is CAS

16. CAS issues

17. What is Future?

18. What is AQS

19. AQS supports two synchronization methods:

20. What is ReadWriteLock

21. What is FutureTask

22, the difference between synchronized and ReentrantLock

23. What is an optimistic lock and a pessimistic lock

24. How does thread B know that thread A has modified the variable?

25, synchronized, volatile, CAS comparison

26. What is the difference between sleep method and wait method?

27. What is ThreadLocal? What is the use?

28. Why wait() method and notify()/notifyAll() method should be called in synchronized block

29. What are the methods for multi-thread synchronization?

30. Thread scheduling strategy

31. What is the concurrency of ConcurrentHashMap

32. How to find which thread uses the longest CPU in the Linux environment

33. Java deadlock and how to avoid it?

34, the cause of deadlock

35. How to wake up a blocked thread

36. How does immutable objects help multithreading?

37. What is multi-threaded context switching

38. What happens if the thread pool queue is full when you submit a task?

39. What is the thread scheduling algorithm used in Java

40. What is the thread scheduler (Thread Scheduler) and time slicing (TimeSlicing)?

41. What is spin

42. What is the Lock interface in Java Concurrency API? What are its advantages over synchronization?

43. Thread safety of singleton mode

44. What is the function of Semaphore?

45. What is the Executors class?

46. ​​Thread class construction method and static block are called by which thread

Shanghai-Ctrip-Java Advanced

1. Describe the principle and mechanism of JVM loading Class files  ?

2. What is a class loader?

3. What are the class loaders?

4. What is the tomcat class loading mechanism?

5. The parent delegation model mechanism of the class loader?

6. Java memory allocation?

7. What is the structure of the Java heap?

8. Briefly describe the changes in the memory area of ​​each version?

9. Tell me about the role of each area?

10. Will there be memory leaks in Java, briefly?

11. Java class loading process?

12. What is GC? Why do we need GC  ?

13. Briefly describe the Java garbage collection mechanism?

14. How to judge whether an object is alive?

15. The advantages and principles of garbage collection, and consider 2 types of recycling mechanisms? What is the basic principle?

16. Deep copy and shallow copy?

17. What is distributed garbage collection (  DGC)? How does it work?

Shenzhen-OPPO-Java Advanced

  1. Tell me about your work experience?
  2. Which module is the project mainly responsible for?
  3. Draw a structure diagram of your project
  4. How does Eureka register for service?
  5. If the service is down or cannot be accessed, I still request the service. What will Eureka do? What will happen?
  6. Talk about Eureka's protection mechanism
  7. Is Ribbon's load balancing internal or external to the service?
  8. How does Ribbon achieve load balancing?
  9. Without Eureka, can I make service requests directly through Ribbon?
  10. How does Hystrix realize fusing?
  11. When the service cannot be accessed, is it directly fuse or downgraded?
  12. How does a fuse appear?
  13. In Springcloud, what is the process for consumers to call providers? Please draw a picture of the working principle of springcloud
  14. What are the cluster modes of Redis?
  15. If you originally read the data in Redis, its data structure has changed, how to deal with it without changing the code, so that the downstream business is not affected?
  16. What are the persistence methods of Redis? Talk about their specific realization,
  17. Did you encounter any problems while using Redis?
  18. What are the memory recovery mechanisms of Redis?
  19. What are the expiration policies of Redis? Brief introduction of different strategies
  20. Talk about Redis's elimination strategy? Can the obsolete algorithm be modified or rewritten on its own?
  21. What is the message middleware used in your project?
  22. How is your Rabbit cluster deployed?
  23. How is the data between Rabbit clusters synchronized? Synchronous or asynchronous?
  24. Do you store the data in a queue on one machine or on multiple machines? why?
  25. What is the internal structure of RabbitMQ? Please draw the architecture diagram of RabbitMQ
  26. Does your company's database have sub-databases and sub-tables? How to achieve it?
  27. What is the basis of Mysql index?
  28. Talk about B+ tree
  29. What is the difference between using an auto ID and UUID as the primary key?
  30. What are the transaction isolation levels of the database?
  31. How do we implement transactions in code?
  32. If in a transaction, the code business process is very long, will there be any problems? Why does this problem occur?
  33. Have you encountered any problems when using the volatile keyword? Why does this problem occur?
  34. Please talk about the underlying implementation principle of volatile
  35. How to create a thread pool? What are the parameters? The realization principle of thread pool
  36. Do you have any questions for us?

Shenzhen-Fengchao Technology-Java Advanced

1. The difference between bio and nio

2. The difference between select and poll

3. The working principle of zookeeper

4.cap theory

  1. Which two theories of the sub-paragraph Manchu cap theory
  2. The parameter configuration of the thread pool, why the java official provides a manual method for the thread pool
  3. The benefits of the distributed framework dubbo, is it possible not to use dubbo. Why use distributed
  4. How to use the seven garbage collectors together
  5. Access to the current limit plan

10. Principles of Using ConcurrentHashMap

  1. Solution to the concurrency problem of map
  2. What is a coroutine, and the main points of implementation

13. Implementation of lru cache using hash map (algorithm)

  1. Graph depth traversal and depth traversal (algorithm)
  2. Basic sorting (algorithm)
  3. Use of design patterns

17.java 8 streaming usage

  1. Talk about b+ tree?
  2. Memory barrier and volatile:

20. The concept of java domain

  1. Concepts in the field of distributed design
  2. How to implement shopping current limit on Double 11 (redis implementation plan)

23. mysql tuning

24.cdn (Live more in different places)

  1. Communication method between processes

26.tcp/ip protocol, http protocol

  1. Write a redis distributed lock:

28. The spread of 7 kinds of transactions in spring is:

  1. Distributed down machine processing scheme (one jump detection)

30. Is the distributed strong consistency, weak consistency, and ultimate consistency under analysis?

31. The difference between dubbo and zookeeper as the registration center. If the registration center is hung up, can consumers still call the service and what call is used

32. Schematic diagram of dubbo (draw a diagram of the relationship between the registration center, consumers, and producers, and state the role of each color)

33. Are multiple threads used in the project?

34. The underlying principle of HashMap (including the underlying data structure, how to expand)

35, the principle of ConcurrentHashMap

36. Implementation of distributed locks

37. Distributed session, how to keep it consistent

38. What are the message middleware used and their differences

  1. We know that hashmap is not thread-safe, so what class can replace it to ensure thread-safety? How do they achieve thread safety?
  2. Talk about a GC mechanism?
  3. Talk about consistent hash?
  4. mybatis basic knowledge;
  5. Basic knowledge of mysql;
  6. How much data does mysql express need to be divided into databases and tables?
  7. hibernate basics.
  8. Talk about the principle of Kafka, why can we guarantee such a high throughput?
  9. What do you know about webservice?
  10. Tell me about your company's git division management plan?
  11. How does mysql sub-table and database?
  12. How do you communicate with the front end?
  13. Talk about the major problems or challenges you usually encounter, as well as your problem-solving ideas and processes. I usually pay attention to the solution of the company's online problems.

Shenzhen-Lexin-Java Advanced

  1. Draw the project architecture diagram
  2. What are the technical points used in the business module where you are in charge?
  3. How to achieve final consistent distributed transactions?
  4. What is the B+ tree structure of the index?
  5. Under what circumstances will the index become invalid? In addition to adding indexes to optimize queries, what other methods are there?
  6. Tell me about the design patterns you know? What design patterns are used in Spring? Have you used any design patterns?

7. TCP three-hand grip and four-stroke mechanism?

8. Https principle?

9. What are the data types of Redis? What is the difference with Memcached?

  1. Is the message queue used? How is it used in the project? How to ensure the reliable delivery of messages?
  2. Talking about Java collections, what implementation classes and data structures are there under each collection?
  3. Introduce a red black tree and a cross-balanced tree.
  4. In jdk1.8, when the ConcurrentHashMap size is larger than 8, it will be converted into a red tree. What is the use? If the size is smaller than 8 through the remove operation, what will happen?
  5. Talk about the java synchronization mechanism, what locks does java have, and the characteristics of each lock?
  6. Talk about how volatile guarantees viability and analyze it from the cpu level.
  7. What order does spring load beans in?
  8. Which objects will be stored in the past?
  9. When is full gc triggered?
  10. Where will oom appear in jvm? What are the possible reasons for oom?
  11. How do we find out which area in the jvm oom comes from?
  12. Do you have experience in jvm tuning? What are the tuning plans?
  13. Have you ever seen any source code? Please draw it.
  14. Have you ever written or read custom classloader?
  15. Introduce a project you have done recently, draw a framework diagram and analyze the business process.
  16. Which books have you usually read?

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Shenzhen-SenseTime-Java Advanced

  1. Ask what to write about your resume, and pay attention to the status and contrast of similar products of the technology used.

2. The relationship between kafka data partitions and consumers, kafka's data offset reading process, how to ensure the order inside kafka, and how to ensure the order of consumers in combination with external components

3.cms garbage collection mechanism

4. Springcloud component functions, internal details, differences from dubbo, dubbo architecture, dubbo load strategy

5. Mapreduce principle

6.nio, bio, sellector/epoll, aio, netty comes with codecs, netty advantage, java memory model

7.akka model

8.java arraylist, linkedlist distinction and realization principle, hashmap and concurrenthashmap distinction and realization principle, concurrenthashmap 1.7 and 1.8 distinction,

Implementation details, linkedhashmap sorting principle, how to ensure data idempotence in applications

9.web.xml listener, filter, servlet loading order. How to load filter without configuring in web and xml

  1. Infinite numbers provide multiple solutions for top K issues

11. A, b, and c three tables, do associative query, how to optimize, can be used as a foreign key, just add a table foreign key to the c table.

12. What is the difference between CourrentHashMap JDK1.7 and JDK1.8?

  1. Threads a, b, c, d run tasks, how to ensure that when a, b, c threads are executed, then d thread will be executed?
  2. How to ensure data consistency in a distributed system?
  3. Which places should be paid attention to when splitting microservices, and how to split them?

16. What components does SpringCloud Family Bucket contain?

  1. Do you know Docker, what is the difference between Docker and virtual machine?
  2. How to communicate between multiple Docker containers on the same host? How to communicate between Docker containers in multiple hosts?
  3. How to optimize the performance of high-concurrency systems? How to prevent oversold inventory?
  4. How to ensure service idempotence?

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Origin blog.csdn.net/m0_46995061/article/details/114582701