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This article mainly explains "what are the practical Java interview questions". The explanation in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what are the practical Java interview questions"?

1. Three minutes to introduce yourself.

Self-introduction is an opening statement of the interview, there is nothing to say about this, but it is suggested that you can write down what you want to express in the form of words, and then recite it skillfully, so that no matter in the telephone interview, video interview or on-the-spot interview can be expressed smoothly and systematically.

two。 What is the most familiar area?

This question gives you a piece of advice! Don't talk about areas you can't do, or the whole interview will be over before it begins. don't say you're good at everything for the sake of performance, so if you can't answer several questions asked by the interviewer, you'll basically be sentenced to death. And the whole impression will not be good, and it will be very difficult to interview in the future. So here we just seek truth from facts, say what we are familiar with, and do not say what we are not familiar with.

What are the common data types of 3.Redis?

The commonly used type of five big data in Redis, String,Hash,List,Set,Sorted Set. Then don't stop talking about these types, you can expand them, and by the way, you can say whether each data type is useful in your own project, where it is used, and why you choose this type. Although it is a question and answer in the process of the interview, you should expand it appropriately and say a little more about what you know, so as to let the interviewer know that you really know. If you ask you what the data types are, you will answer these five, so the interview will be boring, it will be difficult to move forward, and you will not make a good impression on the interviewer.

Do you know the persistence of 4.Redis? There are several ways. What's the difference?

With regard to the persistence of Redis, we have written a special article on our official account. You can take a look at the following interviewer: please tell me how Redis ensures that data is not lost after downtime.

Do you know the three cluster modes of 5.Redis?

About Redis cluster mode, no matter whether you have built it or not, you can tell what you know, master-slave mode, Sentinel mode, cluster mode, and the difference between the three modes.

How is the master-slave data of 6.Redis synchronized?

The master-slave data synchronization of Redis and the above cluster mode can be divided into a separate article, which can be shared separately by Ah Fan later.

What scenarios are used by 7.Redis?

Redis, as a mainstream cache database, uses many scenarios, such as user token storage, hot spot data storage, queues, distributed locks, counters, Bloom filters, etc., combined with the scenarios used in your own project, you can talk to the interviewer.

Why is 8.Redis performing so well?

Redis official text claims that the highest QPS can reach 100, 000, so why can Redis have such high concurrency? The main reason is that Redis adopts multiplexing IO model, and single thread is used to process commands. At the same time, the bottom layer of Redis is written in C language, and the data structure is relatively simple, so it can be so fast.

What are the storage engines of 9.MySQL, and what is the difference between InnoDB and MyISAM?

The main storage engines commonly used in MySQL are InnoDB and MyISAM, as well as Memory, in which the difference between InnoDB and MyISAM has been described in detail on the official account. Interested partners can take a look at the MySQL knowledge points that must be asked in the interview. If you are not ready, collect the brain map quickly!

10. What is a transaction? What are the isolation levels of transactions? Why is the isolation level of the transaction required?

The content of the transaction is also described in detail in the above article, you can go in and have a look.

The content of 11.SQL optimization? How do you do the sub-database and sub-table?

About SQL optimization is also an old topic, in the interview is often asked, about SQL optimization, there is an article is very good, recommended to you, which talked about a lot of optimization points, carefully write down 52 SQL statement performance optimization strategies, suggestions collection

What storage structure is used in the index of 12.MySQL? Why use this?

The index of MySQL is also an unavoidable question in the interview. For more information, please refer to the previous article on the official account. Why do Mysql's common engines use B + tree as the index by default?

What are the default implementations of thread pools in 13.Java, and how do several core parameters work together? What are the rejection strategies?

There is a default implementation of thread pool in Java, but we usually create thread pool manually during daily work. For more information, the interviewer asked me to turn left because of thread pool. Talk about the Java thread pool in the interview

What is the function of volatile and synchronized in 14.Java?

The importance of these two keywords in Java is self-evident. There is no need for A Fan to say anything more. Do you understand these two keywords? Similarly, we've written about the eerie visibility of concurrency.

15. What is the class loading mechanism?

Without saying anything, just look at the article. How does JVM load the Java class? I'm sure you'll understand after reading it.

After reading the above 15 interview questions, it is easy to find a problem, that is, during the real interview, we have written a lot of things before the official account, as long as we digest these things well, and make good use of them during the interview, not to mention that we will be able to get an offer, at least the first few aspects can be very perfect. When you see this, do you think this article is worth collecting? Put it away so that you can take it out and use it before the interview or during the interview.

Project section

The above are some technical details, in fact, there are many things, after all, the field of Java involves a lot of places, such as this kind of interview questions can be asked endlessly. After talking about the technical details, we usually start to ask about the project. Everyone's project is different, and the areas involved are not the same, which is not referential, but some general questions still need to be prepared, such as

What technologies are used in the project and what does the whole framework look like?

What are you mainly responsible for in this project and how do you design it?

Did you encounter any technical difficulties when working on this project? how did you solve it?

What is the QPS after the project is launched, how many users are there? has there been any Fullgc or online OOM? how do you deal with it?

How are modules and modules called before? HTTP or RPC? What is used in the RPC framework? Do you know the principle of its implementation?

What is the purpose of this project? Do you know anything about the industry involved in the project?

The above are all the things you need to know and think about when doing a project every day, and you must know what is involved in the technology. on the last issue, many friends will often ignore it and think it is just a project. What does it have to do with the industry? In fact, this is not the case, understanding the background and value of a project can better help us understand business needs, so as to achieve better implementation, and for some friends who want to develop in a certain direction for a long time, it is even more necessary.

Architectural deployment aspect

Is your project distributed? How is it deployed?

How to improve QPS without adding machines?

How to reduce the time-consuming of network communication between various services or computer rooms?

If there is a sudden failure in the computer room, how to ensure that the data is not lost?

When there is a problem with the downstream service, how to do circuit breaker and current limit to ensure that your service will not be affected?

Thank you for your reading, the above is the content of "what are the practical Java interview questions". After the study of this article, I believe you have a deeper understanding of what the practical Java interview questions have, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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