Preface
The thing is like this. At the beginning of this year, I got a Java interview book from a big blogger, and then I was lying on the plate and eating ashes. Until May, when I had a plan and plan to change jobs, I thought I was going to brush up on the interview questions, so I took out this set of "ash accumulation" interview collections and looked at it. It took me more than a month to see it completely. I started to interview Meituan in mid-July. It looked like five sides. I thought it was hopeless. When I received the offer on the 29th of the month, I was notified to report to the company on August 3 and almost jumped up when I saw the email!
Let me talk about my personal situation. Undergraduates in South China, not 985 and 211, have worked in a small company after graduation. They didn’t make a lot of money but at least not 996. It has been almost three years since then, suddenly thinking about their future. I want to change the status quo, so I am determined to review hard and prepare to change jobs. Of course, in addition to the interview questions, I also reviewed a wave in the early stage.
This article contains two chapters:
(1) 999 pages of Java interview book content;
(2) My Meituan interview experience sharing, including interview questions and answers. However, due to limited space, it cannot be fully displayed. The full pdf version is required. "Click here-send"
The 999-page Java Interview Booklet has cheated me for a full month and a half
1. Java foundation (Tomcat+Mysql+design pattern+concurrency+Netty+JVM)
Take the JVM interview questions as an example:
- Java class loading process?
- Describe the principle mechanism of JVM loading Class files?
- Java memory allocation
- What is GC? Why is GC?
- How to judge whether an object is alive? (Or how to determine the GC object)
- The advantages and principles of garbage collection. And consider 2 recycling mechanisms
- What is the basic principle of the garbage collector? Can the garbage collector reclaim memory immediately? Is there any way to proactively notify the virtual machine for garbage collection?
- Will there be a memory leak in Java? Please describe briefly
- ......
JVM core interview questions (answer + analysis)
2. Distributed (current limit + cache + communication)
Distributed current limit: Zookeeper+Nginx
Distributed cache: mongoDB+memcached+Redis
Distributed communication: RabbitMQ+Kafka
Take Redis as an example:
- What is the difference between redis and memcached? Why is sometimes single-threaded redis more efficient than multi-threaded memcached under high concurrency?
- How does redis master-slave replication work? How to realize the cluster mode of redis? How are redis keys addressed?
- How to design distributed locks using redis? Talk about the realization idea? Can I use zk? How to achieve? What is the difference between these two?
- Do you know the persistence of redis? How is the bottom layer implemented? What are the advantages and disadvantages?
- What are the redis expiration strategies? Does the LRU algorithm know? Write a java code implementation?
- Cache penetration, cache breakdown, and cache avalanche solutions?
- When choosing a cache, when to choose redis and when to choose memcached
- What if the cache is inconsistent with the database?
- How to solve the inconsistency of master and slave databases?
- Common Redis performance problems and solutions?
- What are the data elimination strategies of Redis?
- What are the data structures in Redis?
- If there are 100 million keys in Redis, 10w of them start with a fixed, known prefix. What if you can find them all?
- Have you used Redis as an asynchronous queue and how did you achieve it?
- How does Redis implement delayed queues?
- ......
3. Open source framework (Spring+SpringMVC+MyBatis)
Take Spring as an example:
- What is the Spring framework? What are the main modules of the Spring framework?
- What are the benefits of using the Spring framework?
- What is Inversion of Control (IOC)? What is dependency injection?
- Please explain the IoC in the Spring framework?
- What is the difference between BeanFactory and ApplicationContext?
- How many ways to configure Spring?
- How to configure Spring based on XML configuration?
- How to configure Spring based on Java configuration?
- How to configure Spring with annotations?
- Please explain the life cycle of Spring Bean?
- What is the difference between the scope of Spring Bean?
- What are Spring inner beans?
- Are singleton beans in the Spring framework thread-safe?
- Please give an example of how to inject a Java Collection in Spring?
- How to inject a Java.util.Properties into Spring Bean?
- Please explain the autowiring of Spring Bean?
- Please explain the difference in auto-assembly mode?
- How to enable annotation-based automatic assembly?
- ......
Spring interview questions (answer + analysis)
Spring core knowledge points
4. Microservice architecture (Dubbo+SpringBoot+SpringCloud)
Take SpringBoot as an example:
- What is Spring Boot?
- What are the advantages of Spring Boot?
- What is JavaConfig?
- How to reload changes on Spring Boot without restarting the server?
- What is the monitor in Spring Boot?
- How to disable Actuator endpoint security in Spring Boot?
- How to run Spring Boot applications on custom ports?
- What is YAML?
- How to realize the security of Spring Boot application?
- How to integrate Spring Boot and ActiveMQ?
- How to use Spring Boot to implement paging and sorting?
- What is Swagger? Have you implemented it with Spring Boot?
- What is Spring Profiles?
- What is Spring Batch?
- What is a FreeMarker template?
- How to use Spring Boot to implement exception handling?
- Which starter maven dependencies did you use?
- ......
Spring interview questions (answer + analysis)
Spring core knowledge points
5. Real interview questions for first-line Internet companies over the years (Ali + ByteDance + Meituan + NetEase + Pinduoduo + Jingdong + Station B, etc.)
Take Meituan as an example (partial):
- The difference between List and Set
- How does HashSet guarantee non-repetition?
- Is HashMap thread safe? Why is it not thread safe? (It is best to draw a picture to illustrate that it is not safe in a multi-threaded environment)
- HashMap expansion process
- The difference between HashMap 1.7 and 1.8, explain what optimizations have been made in 1.8, and how?
- Four references to objects
- Three ways to get reflection in Java
- Java reflection mechanism
- The realization principle and difference between Arrays.sort and Collections.sort?
- Application of LinkedHashMap
- Cloneable interface implementation principle
- What is the difference between wait and sleep?
- Tell me about how arrays are allocated in memory?
- ......
Real interview questions for first-line Internet companies (detailed answer version)
Meituan interview questions sharing (5 rounds of pressure surface)
I have compiled the answers in the following interview questions in the document. The answers and analysis are all sorted and summarized after the interview, including personal opinions and thoughts. They are not completely correct and have a certain reference value. If you need the answer, you can share it with a private message [ Interview questions] Get.
Meituan side:
- Introduce yourself and briefly talk about your project;
- Have you encountered a memory leak? How did you solve it?
- What are the basic types of java? Is String a basic type of java? Why should String be final?
- What is the underlying implementation of the reflection mechanism? Dynamic? The dynamic realization principle?
- Do you understand hashmap? Talk about some things related to hashmap? Is hashmap thread safe? Why is it thread safe?
- Do you understand concureenthashmap? How does he achieve thread safety?
- Did you just say 1.8 is based on cas? How to solve the ABA problem of cas?
- Talk about the threading model of JVM? What are these areas for?
- Tell me about the working mechanism of the java class loader? In which area is the class loading performed?
- Talk about the threading model of java?
- Violate understand? What is its principle? Is violate thread safe?
- What are the solutions to ensure thread safety? Talk about the read-write lock, the read of the read-write lock
- What types of database indexes are there? Why use B+ tree for indexing? What is the difference between a composite index and several individual indexes? Do you understand the query optimization of large tables in the database? Do you understand the MVCC mechanism? What's wrong with the MVCC mechanism? How to solve this problem? Have you done mysql slow statement tuning? Tell me how you do it?
- Does redis understand? Do you talk about how to use redis to implement distributed locks?
- The scope of Bean in spring, is the controller of springMVC thread safe? How to ensure thread safety?
- Has the message queue been used? Tell me how do you use it?
- Do you understand computer networks? Let's talk about TCP three-way handshake and four waved hands
- What is the reason for the time_wait state? , What's the harm? How can it be avoided?
- Find the smallest value in a rotated sorted array
Assume that the array sorted in ascending order is rotated at a point unknown in advance.
(For example, the array [0,1,2,4,5,6,7] may become [4,5,6,7,0,1,2]).
Please find the smallest element.
You can assume that there are no duplicate elements in the array.
Example 1:
Input: [3,4,5,1,2]
Output: 1
Example 2:
Input: [4,5,6,7,0,1,2]
Output: 0
Meituan two sides:
- First, ask the project.
- The difference between String, StringBuffer and StringBuilder, why String is immutable, which is thread-safe, StringBuffer and StringBuilder, and what scenarios they are applicable to.
- What is the java class loading process, talk about volatile.
- Do you understand concurrent package? If several threads wait for each other, which concurrency class can be used to achieve this, and what is its principle?
- What do you know about database slow query optimization?
- Talk about the startup process of the spring container?
- Talk about distributed locks. What is the difference in performance based on zookeeper implementation and redis implementation?
- How does Kafka ensure that no messages are lost and no repeated consumption. Know some technologies related to big data?
- Finally wrote the question: jumping game;
Given an array of non-negative integers, you are initially at the first position of the array.
Each element in the array represents the maximum length you can jump at that position.
Determine whether you can reach the last position.
Example 1:
Input: [2,3,1,1,4]
Output: true
Explanation: We can jump 1 step first, get from position 0 to position 1, and then jump 3 steps from position 1 to the last position.
Example 2:
Input: [3,2,1,0,4]
Output: false
Three sides of Meituan:
- How does redis guarantee thread safety in distributed mode?
- The way and difference of redis persistence?
- How does zookeeper implement distributed locks and how to implement other distributed locks?
- How to use Kafka to ensure the orderliness of messages?
- What does database optimization include? MySQL optimization, talk about two examples of your optimization.
- For the most technically difficult projects, introduce the relevant core design process.
- At work, if you encounter a technical bottleneck that cannot be solved, what is your solution?
- What is your future career plan?
Meituan four sides:
- Self introduction
- Project Introduction
- How to manage project members?
- When disagreements, how to communicate and persuade development members? for example
- How to ensure the progress of the project?
- The principle of database index?
- Non-clustered index and clustered index?
- Precautions for using the index?
- Joint index
- Explain the leftmost matching principle from the bottom
- Does Mysql optimize the joint index? Will the order be adjusted automatically? Which version is optimized?
- Redis application
- Redis persistence method and principle
- Technology selection, a new technology and a stable old technology, how would you choose, and what are your considerations?
- The three blogs of the Meituan Dianping technical team that impressed you most
- What new technology are you learning recently?
- How did you get in touch with a new technology?
- Which books will you read?
- How to choose the book to read?
Meituan HR noodles:
- Do you usually use Meituan? How is the evaluation?
- What are you doing with Meituan?
- What do you think of the Meituan platform?
- Do any friends interview or work for Meituan?
- Which companies are still interviewing?
- Q. What do you think is your experience in interviews at various companies?
- Salary expectations
to sum up
I am very lucky, but I also firmly believe that good luck is always reserved for those who are prepared. Therefore, when you and I have goals, you need to keep working hard. If you are prepared, you will naturally get what you want and your goals will eventually be achieved. But if you have no thoughts but no action, you will be anxious when you are 30 years old and be eliminated by the market sooner or later.
The above content, I only hope that all colleagues in the same industry can have a clear self-awareness. If programmers want to be irreplaceable, they must improve their skills.
Whether it is this 999-page Java Interview Collection or the other documents I have on hand, it can be packaged and shared with you, as long as you support me a lot, and support yourself a lot!
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