Summary of the most complete Java interview questions and answers in 2023

Preface

It is still necessary to answer some targeted questions before the interview. Many friends have strong practical skills but weak theory. If you do not prepare before the interview, you will suffer a lot. Here we have compiled some frequently asked interview questions. I hope it will help you review before the interview and find a good job. It will also save you time in searching for information online to study.

Compilation of Java interview questions from Issue 1-100

Compilation of Java interview questions for period 101-110

Interviewer: Why is it not recommended to use equals to determine whether objects are equal?

Interviewer: Why does MySQL not recommend using join?

Interviewer: How does SpringBoot customize its own conditional annotations and automatic configuration?

Interviewer: How many of the eight heavyweight locks can you catch?

Interviewer: I asked ten people who tend to lock, how many can you catch?

Interviewer: The machine is down. How does Redis avoid data loss?

Interviewer: What optimizations has the JVM made on locks?

Interviewer: What is scaffolding? Why is scaffolding needed? What are the commonly used scaffoldings?

Interviewer: Even if the database deletes the table data, the disk space is still occupied. Why?

Interviewer: How to choose between Zabbix and Prometheus?

Compilation of Java interview questions for period 111-120

Interviewer: How do Redis and Mysql ensure data consistency?

Interviewer: Let’s talk about common multi-thread lock strategies.

Interviewer: Will using try-catch to catch exceptions affect performance?

Interviewer: What is the difference between BIO, NIO and AIO?

Interviewer: Does MySQL’s auto-incrementing primary key have to be continuous?

Interviewer: How to read 1 million data from MySQL for processing?

Interviewer: Tell me about the @Cacheable cache annotation in Spring?

Interviewer: Why is Kafka so fast?

Interviewer: What do you understand by System.out.println()?

Interviewer: Let’s talk about the SPI mechanism in SpringBoot

Compilation of Java interview questions for period 121-130

Interviewer: When talking about the nesting of transactions in Spring?

Interviewer: Tell me some ways to start asynchronous threads in Java?

Interviewer: Do you know all the 7 ways to create a thread pool?

Interviewer: How to set JVM parameters with 1 million login requests per day and 8G memory?

Interviewer: How many TCP connections can a server support?

Interviewer: In Java's loop traversal, how to ensure that each loop body is a separate transaction?

Interviewer: Tell us about symmetric encryption, asymmetric encryption, and hybrid encryption?

Interviewer: How to measure code execution time in Spring Boot

Interviewer: Talk about the distributed consistency mechanism?

Interviewer: Let’s talk about the SpringBoot startup process

Compilation of Java interview questions for period 131-140

Interviewer: How to optimize the performance of the details page?

Interviewer: Can you tell the difference between PO, VO, BO, DTO and POJO?

Interviewer: Will SELECT COUNT(*) cause a full table scan?

Interviewer: What is the snowflake algorithm? What's the principle?

Interviewer: MySQL accidentally deleted table data, how to quickly recover the lost data?

Interviewer: What is the relationship and difference between processes and threads?

Interviewer: What are the ways to stop services in Spring Boot?

Interviewer: String s = new String("xyz") How many objects are created?

Interviewer: Why can indexes make queries faster?

Interviewer: How to implement a middleware that separates reading and writing?

Compilation of Java interview questions for period 141-150

Interviewer: Tell me about common multi-thread lock strategies?

Interviewer: Tell us about cache penetration? Cache breakdown? Cache avalanche?

Interviewer: What optimizations has the JVM made on locks?

Interviewer: How does the server prevent duplicate payments for orders?

Interviewer: What are the optimization ideas for Nginx? How to prevent hotlinking on a website?

Interviewer: Tell me about the role of API gateway? How do enterprises apply API gateways?

Interviewer: Do you know the principle of Spring lazy-init lazy loading?

Interviewer: Why merge HTTP requests? what is the benefit?

Interviewer: Could you please tell me how to avoid placing repeated orders?

Interviewer: What is the execution order of Spring annotations @After, @Around, @Before?

Compilation of Java interview questions for issues 151-160

Interviewer: How to design API return codes (error codes)?

Interviewer: How to solve the data dependency problem between microservices?

Interviewer: What message modes does RabbitMQ have?

Interviewer: There are 4 billion QQ accounts, and the memory is limited to 1G. How to remove duplicates?

Interviewer: How are Cookies and Sessions linked?

Interviewer: There are a lot of logs in the Linux server. How to quickly locate errors?

Interviewer: What are the key points in designing a high-traffic and high-concurrency system?

Interviewer: How does the SpringBoot project design the business operation log function?

Interviewer: Briefly explain the differences between blocking IO, non-blocking IO, and IO reuse?

Interviewer: What is the maximum number of rows of data in a single MySQL table? Why?

Compilation of Java interview questions for Issues 161-170

Interviewer: Let’s talk about the differences and uses of @NotEmpty, @NotBlank, and @NotNull in Spring

Interviewer: What are the optimization ideas for Nginx? How to prevent hotlinking on a website?

Interviewer: Why doesn’t the database connection pool use IO multiplexing?

Interviewer: String s = new String("xyz") How many objects are created?

Interviewer: Tell me about the three paging methods of MyBatis?

Interviewer: Will select...for update lock tables or rows?

Interviewer: Service in Spring has multiple implementation classes. How to inject them?

Interviewer: Why does Redis need to save the same data twice?

Interviewer: Can Redis replace MySQL as a database?

Interviewer: How does Spring ensure transaction consistency in a multi-threaded environment?

Compilation of Java interview questions for issues 171-180

Interviewer: Tell me the difference between for and foreach?

Interviewer: Do you know all the four deployment strategies of microservices?

Interviewer: How to use enumerations to eliminate if/else in Java?

Interviewer: Have you avoided the hidden traps of Arrays.asList()?

Interviewer: What is the difference between Class.forName and ClassLoader in Java?

Interviewer: Talk about how to design the compensation mechanism in distributed systems?

Interviewer: Tell me about the Spring Bean instantiation process?

Interviewer: Why is the first call to Feign so slow?

Interviewer: How to traverse massive data in Redis?

Interviewer: Can synchronized prohibit instruction reordering?

Compilation of Java interview questions for period 181-200

Interviewer: Why does MySQL not recommend using join?

Interviewer: Why does MySQL not recommend using NULL as the column default value?

Interviewer: What are the maximum number of connections and the maximum number of concurrencies in SpringBoot?

Interviewer: Why did Tomcat break the Java parent delegation mechanism?

Interviewer: There are 1 million data queries, but paging cannot be used. How to optimize it?

Interviewer: What are the problems with Redis distributed locking? How to solve?

Interviewer: What is the difference between SpringBoot packaging into jar and war when packaging and deploying?

Interviewer: How to design a robust flash sale system?

Interviewer: Why is list.sort() faster than stream().sorted()?

Interviewer: Why does post send two requests?

Interviewer: How to use Redis to build a feed streaming system?

Interviewer: You use Stream every day, so do you know the implementation principle of Stream?

Summarize

All interview questions are not static. The interview questions are just a reference for everyone. The most important thing is to increase your knowledge reserve and be prepared.

We have specially sorted out Java interview questions in categories to facilitate your daily review and collection. I hope that friends who are preparing for interviews can find their favorite jobs smoothly! ! !

• Java basic interview questions (1)

• Java basic interview questions (2)

• Java multithreading and concurrent programming

• JVM interview questions

• MySQL interview questions

• Spring interview questions

• Spring Boot interview questions

• Spring Cloud interview questions

• Redis interview questions

• MyBatis interview questions

• ZooKeeper interview questions

• Dubbo interview questions

• Elasticsearch interview questions

• kafka interview questions

• RabbitMQ interview questions

• Linux interview questions

• Microservices interview questions

These Java interview questions are all organized and packaged →: Click to download

All interview questions are not static. The interview questions are just a reference for everyone. The most important thing is to increase your knowledge reserve and be prepared.

I hope that friends who are preparing for interviews can find their favorite jobs smoothly! ! !