The latest "Java Interview Assault Core Manual" for 2023 Golden Nine and Silver Ten is released, covering 1309 Java interview questions from major manufacturers!

foreword

Judging from the current general environment, it is much more difficult to succeed in job-hopping than in previous years. An obvious feeling: the competition in the Internet industry is becoming more and more severe, and interviews are also becoming more and more difficult. Many large companies, such as Ali, Tencent, and Huawei, have significantly reduced their recruitment quotas, but the interview threshold has been raised again and again. In fact, if you want to survive, you must There must be elimination, survival of the fittest, and survival of the fittest. This is the eternal law; what you and I have to do is to continue to cultivate, improve the depth and breadth of technology, and follow the general environment so that we will not be eliminated and better. To adapt to the development of society and major enterprises

I believe everyone knows that interviews are becoming more and more difficult now. There are more and more interview questions to memorize. The investigation is getting more and more detailed and the bottom is getting lower and lower. It is obvious that we want us to build an aircraft carrier with bare hands! It's really embarrassing for us programmers.

In many cases, the questions asked by the interviewer will be different from the questions in the "question bank" prepared by myself. Even after a review, I still don't know where to start the next interview.

For this reason, I specially compiled a "Java Interview Assault Core Manual" to share with you, covering: Java basics, JVM, multithreading, MySQL, spring, springboot, springcloud, Dubbo, Mybatis, Redis, algorithms, microservices, distribution More than 25 technical fields, such as the brain map of technology, etc... The quality is very high! ! !

This new version of the document is very comprehensive, covering Java basics, Java collections, JavaWeb, Java exceptions, OOP, IO and NIO, reflection, annotations, multithreading, JVM, MySQL, MongoDB, Spring family buckets, computer networks, distributed architecture, Redis, Linux, git, front-end, algorithm and data structure, MyBatis, RocketMQ, Netty, Dubbo, Zookeeper, distributed cache, data structure, etc. 1309 interview questions, the content is very rich, and has helped many people win offers from Internet first-line companies. Let me share it with you.

Because there are too many details in the document, only some chapters of knowledge points have been edited for a rough introduction, and there are more detailed contents in the small nodes of each chapter!

JavaOOP

What is B/S architecture? What is C/S Architecture
What development platforms are available for Java?
What is JDK? What is JRE?
What are the characteristics of the Java language
The difference between object-oriented and procedural-oriented
What are data structures?
What are the data structures in Java?
What is OOP?
What is the relationship between classes and objects?
There are several data types in Java

Java collections/generics

The difference between ArrayList and linkedList
The difference between HashMap and HashTable
Collection package structure, the difference from Collections
Generic common features (to be added)
Talk about the difference between List, Set and Map
What is the difference between Array and ArrayList?
What are the characteristics of Map
The collection is stored in the Java.util package, and there are mainly several interfaces
What is the list interface
Talk about ArrayList (array)

java exception

What are the two types of exceptions in Java?
How many exception handling mechanisms are there?
How to customize an exception
try catch finally, there is return in try, is finally still executed?
Excption and Error package structure
The difference between Thow and thorws
What is the difference between Error and Exception?
What is the difference between error and exception

IO and NIO in Java

IO streams in Java?
Difference between Java IO and NIO
What are the commonly used io classes
The difference between byte stream and character stream
Blocking IO model
Non-blocking IO model
Multiplexed IO Model
Signal Driven IO Model
Asynchronous IO model
JAVA NIO

java reflection

In addition to using new to create objects, what other methods can be used to create objects?
Is it more efficient to create objects through Java reflection or to create objects through new?
The role of java reflection
Where will the reflection mechanism be used?
Implementation of reflection:
A class that implements Java reflection:
Advantages and disadvantages of the reflection mechanism:
Java Reflection API
Reflection usage steps (get Class object, call object method)
There are several ways to get the Class object
Dynamically create object instances using reflection

Java serialization

What is java serialization, how to achieve java serialization?
Save (persist) the object and its state to memory or disk
Serialized objects are persisted as byte arrays - static members are not
Serialize user remote object transfer
Serializable implements serialization
writeObject and readObject custom serialization strategy
Serialized ID
Serialization does not save static variables
The Transient keyword prevents the variable from being serialized to the file
Serialization (implemented in deep clone one)

Multithreading & Concurrency

There are several ways to implement multithreading in Java
Inherit the Thread class
Implement the Runnable interface.
ExecutorService, Callable, Future have return value thread
Based on thread pool
4 thread pools
How to stop a running thread
What is the difference between notify() and notifyAll()?
What is the difference between sleep() and wait()?
What is volatile? Can order be guaranteed?

JVM

Will there be a memory leak in java, please describe briefly.
In 64-bit JVM, what is the length of int?
Difference between Serial and Parallel GC?
32-bit and 64-bit JVM, what is the length of int type variable?
Difference between WeakReference and SoftReference in Java?
What does the JVM option -XX:+UseCompressedOops do? why use
How to judge whether the JVM is 32-bit or 64-bit through a Java program?
What is the maximum heap memory for 32-bit JVM and 64-bit JVM respectively?
What's the difference between JRE, JDK, JVM, and JIT?
Explain Java heap space and GC?

Mysql

database storage engine
InnoDB (B+ tree)
TokuDB (Fractal Tree-node with data)
Memory
What are the database engines
The difference between InnoDB and MyISAM
index
Common indexing principles are
What are the three normal forms of the database
First normal form (1st NF - columns are not subdivided)

Redis

What is Redis?
How is Redis different from other key-value stores?
Redis data types?
What are the benefits of using Redis?
What are the advantages of Redis over Memcached?
What are the differences between Memcache and Redis?
Is Redis single-process and single-threaded?
What is the maximum capacity of a smart storage of type string?
Redis persistence mechanism
Cache avalanche, cache penetration, cache warm-up, cache update, cache downgrade, etc.

Memcached

What is Memcached and what does it do?
What are the application scenarios of the memcached service in the enterprise cluster architecture?
How to realize Memcached service distributed cluster?
What are the characteristics and working principle of Memcached service?
Briefly describe the principle of Memcached memory management mechanism?
How does memcached work?
What is the biggest advantage of memcached?
memcached and MySQL query
Compared with the server's local cache (such as PHP's APC, mmap files, etc.), what are the advantages and disadvantages of memcached?
What is the cache mechanism of memcached?
How does memcached implement redundancy mechanism?

MongoDB

What is mongodb?
What are the characteristics of mongodb?
What do you mean by NoSQL database? What is the difference between NoSQL and RDBMS? Why use and not use NoSQL database? Tell me about the advantages of NoSQL database?
What are the types of NoSQL databases?
What is the most basic difference between MySQL and MongoDB?
How do you compare MongoDB, CouchDB and CouchBase?
What makes MongoDB the best NoSQL database?
Will journal playback have problems when the entry is incomplete (for example if one happens to crash midway)?
What is the role of analyzers in MongoDB?
What is a namespace?

Spring

What are the main features of the different versions of Spring Framework?
What is Spring Framework?
List the advantages of Spring Framework.
What are the different features of Spring Framework?
How many modules are there in Spring Framework and what are they?
What is a Spring configuration file?
What are the different components of a Spring application?
What are the ways to use Spring?
What is the Spring IOC container?
What is Dependency Injection?

Spring Boot

What is Spring Boot?
Why use Spring Boot
What are the advantages of Spring Boot?
Which is the core annotation of Spring Boot? Which annotations does it mainly consist of?
What are the ways to run Spring Boot
How to understand Starters in Spring Boot?
How to run some specific code when Spring Boot starts?
Does Spring Boot need a standalone container to run?
What are monitors in Spring Boot?
How to implement exception handling with Spring Boot?

Spring Cloud

What is Spring Cloud?
What are the advantages of using Spring Cloud?
What does service registration and discovery mean? How does Spring Cloud implement it?
What is the meaning of load balancing?
What is Hystrix? How does it achieve fault tolerance?
What is a Hystrix circuit breaker? do we need it
What is Netflix Feign? What are its advantages?
What is Spring Cloud Bus? do we need it
What are microservices
What is a service circuit breaker? What is service degradation

RabbitMQ

what is rabbitmq
Why use rabbitmq
Scenarios using rabbitmq
How to ensure that messages are sent to RabbitMQ correctly? How to ensure that the receiver of the message consumes the message?
How to avoid repeated delivery or consumption of messages?
What transport is the message based on?
How is the message distributed?
How are messages routed?
How to ensure that messages are not lost?
What are the benefits of using RabbitMQ?

Dubbo

Why use Dubbo?
What are the layers of Dubbo's overall architecture design?
What communication framework is used by default, and are there any alternatives?
Is the service call blocking?
What registry is generally used? Is there another option?
What serialization framework is used by default, and what else do you know?
What is the principle that the service provider can implement failure proposal?
Why does the service launch not affect the old version?
How to solve the problem that the service call chain is too long?
Tell me about the core configuration?

MyBatis

What is Mybatis?
Advantages of Mybaits
Disadvantages of the MyBatis framework
MyBatis Framework Applicable Occasions
How is MyBatis different from Hibernate?
What is the difference between {} and ${}?
What should I do if the attribute name in the entity class is different from the field name in the table?
How to write fuzzy query like statement?
Usually an Xml mapping file will write a Dao interface corresponding to it, what is the working principle of this Dao interface? Can the method in the Dao interface be overloaded when the parameters are different?
How to get the auto-generated (primary) key value?

ZooKeeper

What is Zookeeper?
How does Zookeeper guarantee the distributed consistency characteristics?
What does ZooKeeper provide?
Zookeeper file system
ZAB protocol?
Four types of data node Znode
Zookeeper Watcher mechanism--data change notification
Client registers Watcher implementation
Server-side processing Watcher implementation
Client callback Watcher

data structure

stack
queue
Linked list (Link)
Hash Table
sort binary tree
prefix tree
red black tree
B-TREE
bitmap

Elasticsearch

How much do you know about elasticsearch, talk about your company's es cluster architecture, index data size, how many fragments, and some tuning methods.
What is the inverted index of elasticsearch
What should I do if there is too much elasticsearch index data, how to tune and deploy
How elasticsearch implements master election
Describe in detail the process of Elasticsearch indexing documents
Describe in detail the process of Elasticsearch search?
What are the optimization methods for Linux settings when Elasticsearch is deployed
What is the internal structure of lucence?
How does Elasticsearch realize the Master election?
Among the nodes in Elasticsearch (for example, there are 20 in total), 10 of them choose a master, and the other 10 choose another master, what should I do?

Kafka

What is Kafka
Partition's data file (offset, MessageSize, data)
Data file segmentation segment (sequential read and write, segment command, binary search)
Load balancing (partitions will be evenly distributed to different brokers)
Batch sending
Compression (GZIP or Snappy)
consumer design
Consumer Group
How to get a list of topic topics
What is the command line for producer and consumer?

microservice

What are the advantages of microservice architecture?
What are the characteristics of microservices?
When is the best time to design microservices?
How does microservices architecture work?
What are the pros and cons of microservice architecture?
What is the difference between monolithic, SOA and microservices architecture?
What challenges do you face when using microservices architecture?
What are the main differences between SOA and Microservice Architecture?
What are the characteristics of microservices?

Linux

What symbol is used for the absolute path? What is the current directory and the upper directory? What is the main catalog? What order is used to switch catalogs?
How to check the current process? How to perform exit? How to check the current path?
How to clear the screen? How to exit the current command? How to implement sleep? how to check when
What does the Ls command do? What parameters can be taken and what is the difference?
What are the commands to view the file
List several commonly used Linux commands
How do you usually check the log?
Create soft links (shortcuts), and commands for hard links
What command is used to create the directory? What command is used to create the file? What order do you use to copy files?
What commands are available to view the contents of a file?

at last

Interview, hard or not? Is the end result good or bad? It depends on the interviewer's background (aura + skills), mentality and cognition, and communication skills. And some mainstream large-scale Internet company interviews (Alibaba, JD.com, Meituan, Didi) require you to show your abilities during the interview, so as to gain the appreciation and affirmation of the interviewer.

And programmers need to go through layers of interviews when applying for a job. As the saying goes, sharpening a knife does not cut firewood by mistake, and doing a good job of preparation before the interview can help you better deal with the interviewer's questions and emergencies during the interview.