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This article mainly explains "what are the JAVA interview questions". Friends who are interested may wish to have a look. The method introduced in this paper is simple, fast and practical. Next, let the editor take you to learn "what are the JAVA interview questions?"

First of all, we need to understand the fact that a key factor in recruitment is to find future colleagues for ourselves, and to find people who are better than us at the same level. the interview is a process of two-way choice and communication.

Just like some of us feel that we are very good, but can not get offer, while others can get offer for a dish, we call it metaphysical offer. When we encounter this situation, we should not feel any indescribable mood, just follow the fate!

Editor, there are reference answers to Java interview questions here. I need you to come down and learn one by one!

I. prologue

Briefly introduce your work experience and responsibilities, the main work content in school or work, and the main content you are responsible for. (your information is clearly written on your resume, and what you can answer is best written on it. Ambiguity is not very clear, it is best not to write, or you will be asked very embarrassingly)

Introduce the projects or platforms that you are most satisfied with and have technical highlights, focusing on the technical details of which part you are responsible for; (mainly whether there is a clear description of what you have done)

II. Java Foundation

What is a string constant pool?

Why is String immutable?

String s = new String ("xyz"); how many objects have been produced, let's talk about them from the perspective of JVM?

Do you know why String is inefficient in stitching strings?

Do you really know the common API of String?

Does subString () in Java really cause memory leaks?

Analysis of final keyword in Java?

Analysis of static keyword in Java?

What do you know about the volatile keyword in Java?

Is iTunes + thread-safe? How to solve thread safety?

Deeply analyze the thread safety principles of iTunes + and + + I from the bytecode point of view.

Please talk about what is CAS?

Look at the implementation principle of ArrayList from the source code point of view?

The implementation of handwritten LinkedList to thoroughly figure out what is a linked list?

What are the rules for passing method parameters in Java?

What is the difference between throw and throws in Java?

What's the difference between reloading and rewriting?

How to realize the handwritten ArrayList in the written examination?

Which holes have you stepped on in the finally statement block?

Why is it necessary to override the equals method as well as the hashCode method?

What is the difference between equals () and =?

The difference between StringBuffer and StringBuilder, from the point of view of source code?

Do you know the data structure of HashMap?

Why must the array length of HashMap be the power of 2?

When will HashMap be expanded and its expansion mechanism?

The key of HashMap usually uses strings, can you use other objects?

Can both key and value of HashMap be null? If key can be null, how does it find the value?

Is HashMap thread safe? How to achieve thread safety?

Analyze the principle of HashSet implementation from the point of view of source code?

What is the difference between the implementation principles of HashTable and HashMap?

Can you really use the String method intern ()?

What is automatic unpacking?

The difference between String.valueOf and Integer.toString?

3. Java multithreading

How many stages does the life cycle of a thread include?

How many ways can multithreading be implemented?

Please talk about what is a process and what is a thread?

Do you start the thread with the start () method or the run () method?

Talk about thread safety, what to achieve thread safety, how to achieve thread safety?

The difference between sychronized and Lock?

What is the difference between sleep () and wait ()?

In-depth analysis of the implementation principle of ThreadLocal?

Have you seen the AbstractQueuedSynchronizer source code reading, please tell me the principle of implementation?

Talk about the understanding of synchronized bias lock, lightweight lock and heavy lock?

Realize the producer-consumer model in three ways?

At the JVM level, how does sychronized ensure thread safety?

At the JDK level, how does sychronized ensure thread safety?

How to write a thread-safe singleton?

Implement a custom Lock through AQS?

When will OOM occur in ThreadLocal? Why?

Why are wait, notify, and notifyAll methods not in the thread class?

Do you really understand CountDownLatch and CyclicBarrier usage scenarios?

There is a deadlock, how to troubleshoot the location problem?

The difference between notify and notifyAll?

What is the difference between thread pool startup threads submit and execute?

Is SimpleDateFormat thread safe? How to solve?

Please talk about the underlying implementation principle of ConcurrentHashmap?

What is the difference between using synchronized to modify static methods and non-static methods?

When a thread enters a synchronized method of an object, can other threads enter the object's method?

The principle of thread pool, why create thread pool? How to create a thread pool?

What are the core parameters for creating a thread pool? How to configure the size of the thread pool reasonably?

What is the difference between synchronized-modified static methods and non-static methods?

IV. Java Web

What is the Servlet,Servlet lifecycle approach?

What is Session and Cookie, and what is the connection between them?

What are the eight implicit objects of JSP?

What is the scope of the four domain objects of JSP?

What is the difference between Post and Get requests?

What's the difference between forwarding and redirection?

JSP custom label, how to achieve circular printing function?

What is the difference between Http1.0 and Http1.1?

What's the difference between interceptor and filter?

5. JVM interview questions

How is the JVM memory area divided?

How are objects created in the JVM heap?

The structure of the JVM object?

JVM garbage collection-how can I tell if an object is garbage?

What are the JVM garbage collection algorithms?

What are the JVM garbage collectors?

How is JVM memory allocated?

Analyze the loading process of a class from an interview question?

JVM parent appointment mechanism?

What are the objects that JVM can be used as GC Root?

Please write a few pieces of code that can cause memory overflow, memory leak, stack overflow?

What conditions can lead to Full GC?

How to locate frequent GC problems or memory overflow problems?

VI. SQL performance optimization

What is the three paradigms of database?

The transaction, ACID and isolation level of the database?

Which three situations are easy to occur without considering the isolation of transactions?

The principle of database connection pool?

What is B-Tree?

What is B+Tree?

MySQL database index structure?

What is an index? What conditions are suitable for indexing? What conditions are not suitable for indexing?

What are the reasons for index failure? How to optimize to avoid index failure?

How does MySQL start slow query logs?

How does MySQL use show Profile for SQL analysis?

How can a slow SQL be optimized and how can performance be analyzed through Explain+SQL?

What are row locks, table locks, read locks, and write locks, and what are their respective characteristics?

Under what circumstances do row locks change table locks?

Under what circumstances will a gap lock occur?

Tell me about your understanding of the use of in and exists of MySQL.

What are the database engines of MySQL, and how to determine which storage engine to use in the project?

What is the difference between count (*), count (column name) and count (1)?

The difference between union and union all?

VII. Spring framework

IOC and AOP mechanisms of Spring?

What is the difference between Autowired and Resource keywords in Spring?

There are several ways of dependency injection, and what are they?

How does the Spring container manage Bean components?

How to create a Spring container?

Spring cyclic injection?

Spring transaction classification?

What are the propagation characteristics of Spring transactions?

What is the isolation level of Spring transactions?

What are the notification types of Spring?

VIII. SpringMVC framework

SpringMVC complete workflow, familiar with the source code process?

How does SpringMVC handle JSON data?

SpringMVC interceptor principle, how to customize the interceptor?

How does SpringMVC map the request to the method? Combined with the source code?

What are the common comments on SpringMVC?

What is the difference between a SpringMVC container and a Spring container?

Is the controller of SpringMVC in singleton mode? if so, what's the problem and how to solve it?

IX. MyBatis framework

What is the difference between # and $in MyBatis?

The principle and invalidation of MyBatis first-level cache?

What is the use of MyBatis secondary cache?

The principle of MyBatis interceptor?

Have you seen the MyBatis source code, please tell me how it works?

Advanced part of Java

Dubbo load balancing strategy?

Zookeeper is used as a registry in Dubbo. If the registry cluster is down, can publishers and subscribers still communicate with each other?

A complete introduction to the link of a call to Dubbo?

Could you tell me the principle of SpringBoot automatic assembly?

Have you ever used SpringCloud? please tell me the difference between SpringCloud and Dubbo.

What is WebService and how to develop interfaces based on WebService?

Talk about the distributed transaction application scenario in the project?

How to implement distributed locks using Redis?

Could you talk about the principle of single sign-on?

How is Tomcat optimized?

How does the background system prevent requests from being submitted repeatedly?

What are the common Linux commands?

What is the dependency, inheritance, and aggregation of Maven?

What is the difference between a Git staging area and a workspace?

How does Git create, roll back, and undo versions?

What are the common design patterns?

11. Other

What source code have you seen? And then ask some detailed questions according to the source code you said? (here mainly examines whether the interviewer has the spirit to study the technology, or only stays on the surface, or memorizes a few facial scriptures. For many interviewers with obsessive-compulsive disorder, if you haven't even read the source code, you will basically pass! )

What are the more challenging problems encountered in the project and how to solve them? (this is very controversial, on the one hand, you can't even solve a complex problem, what do you want you to do here, and that is, my ability is great, but the company doesn't have a business scene for me to show! It depends on the interviewer you meet. Good luck! )

So far, roughly sort out some of the interviewer's high-frequency Java interview questions, hoping to be helpful to everyone! In fact, there are many, only part of the finishing, follow-up slowly make up, please look forward to.

At this point, I believe you have a deeper understanding of "what are the JAVA interview questions?" you might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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