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1. Common questions in written test?

The interview questions above are basically linked to the interview questions. Let me just mention a few points:

  1. Write SQL: Writing SQL often looks at group by, inner join, and outer join.
  2. Handwritten code: handwritten code in general singleton, sorting, threads, consumer producers. I suggest that the sorting algorithm in addition to bubble sort, it is best to write a kind of other sort code by hand. Think about it: if the average interviewer writes bubble sort, and you write quicksort/heap sort, you’ll make a good impression.

2. Interview process?

  1. Let you introduce yourself
  2. Ask about Java basics
  3. Ask the project
  4. Situational problems, such as: one of your functions in the production environment, server pressure suddenly increased, how to troubleshoot.
  5. What do you want to ask the interviewer

3. What are common interview questions?

1) Set related questions (required) :

  • The underlying implementation of HashMap, LinkedHashMap, ConcurrentHashMap, ArrayList, LinkedList.
  • Difference between HashMap and Hashtable.
  • ArrayList, LinkedList, Vector.
  • The difference between HashMap and ConcurrentHashMap.
  • The difference between HashMap and LinkedHashMap.
  • Is HashMap thread safe?
  • How ConcurrentHashMap is thread safe.

2) Multi-threaded concurrency related questions (must ask) :

  • Three ways to create a thread.
  • What is thread safety?
  • The difference between Runnable and Callable interfaces.
  • The difference between wait and sleep methods.
  • Synchronized, Lock, ReentrantLock, ReadWriteLock.
  • This section describes the CAS(Lockless technology).
  • The role and mechanism of the volatile keyword.
  • What ThreadLocal is.
  • Four ways to create a thread pool.
  • The inner workings of ThreadPoolExecutor.
  • How to ensure thread safety in distributed environment.

3) JVM-related issues:

  • Introduce garbage collection mechanisms (when, to what, and what).
  • Garbage collection algorithms, their characteristics.
  • The process of class loading.
  • Parental delegation model.
  • What class loaders are available.
  • Can you write a class called java.lang.string?

4) Design pattern-related questions (required) :

  • Ask what design patterns you are familiar with
  • Then ask you specific implementation and extension questions about a design pattern.

5) Database related questions, for Mysql (required) :

  • Give questions to write SQL by hand.
  • Have experience in SQL optimization.
  • Mysql index data structure.
  • SQL how to optimize.
  • The execution order of SQL keywords.
  • What kind of indexes are there?
  • When to (or not) build an index.
  • Explain which columns are included.
  • Explain what types of values are available in the Type column.

6) Framework-related issues:

  • The difference between Hibernate and Mybatis
  • Differences between Spring MVC and Struts2.
  • What design patterns Spring uses.
  • What AOP is primarily used to do in Spring.
  • The way Spring injects beans.
  • What is IOC and what is dependency injection?
  • Is Spring singleton or multi-instance? How to modify?
  • Spring transaction isolation level and propagation.
  • Mybatis/Hibernate caching mechanism
  • # and $in Mybatis mapper file.
  • ResultType and resultMap in the Mapper file of Mybatis.
  • Mybatis DAO layer interface does not write implementation class, Mapper method and DAO interface method are bound together, how is its internal implementation.

7) Other problems:

  • Introduces downstacks and queues.
  • IO and NIO.
  • The difference between interfaces and abstract classes.
  • Int and Integer auto unpacking/boxing related issues.
  • Constant pool-related issues.
  • == and equals.
  • The difference between overloading and overwriting.
  • StringBuilder and StringBuffer.
  • Are static variables, instance variables, local variables thread safe? Why?
  • Which to execute when try, catch, and finally all have return statements?
  • B trees, binary trees.
  • What are the four letters of Ajax?
  • What is the full name of XML?
  • Implementation of distributed lock.
  • Distributed Session storage solution.
  • Common Linux commands.

I would like to share with you my review of the interview materials to add assistant VX: Yunduoa2019 or scan the qr code below to get it by yourself

  • Part I: Java Basics – Intermediate – Advanced

 

  • Part 2: Open Source Framework (SSM: Spring+SpringMVC+MyBatis)

 

  • Part 3: Performance Tuning (JVM+MySQL+Tomcat)

 

  • Part four: Distributed (limiting: ZK+Nginx; Cache: Redis+MongoDB+Memcached; Communication: MQ+ Kafka)

 

  • Part 5: Microservices (SpringBoot+SpringCloud+Dubbo)

 

  • Part six: Others: Concurrent programming + design patterns + data structures and algorithms + networks

Vx: Yunduoa2019 or scan the following two-dimensional code to obtain it by yourself

  • Java architecture advanced frame construction base (Java foundation + concurrent programming +JVM+MySQL+Tomcat+ network + data structure and algorithm)

 

  • Java Architecture advanced open source framework (Design Pattern +Spring+SpringMVC+MyBatis)

 

 

 

 

 

Vx: Yunduoa2019 or scan the following two-dimensional code to obtain it by yourself

 

  • Distributed Architecture (ZK/Nginx + Redis/MongoDB/Memcached) + Communication (MQ/kafka)

 

 

 

 

 

  • Java Architecture Advanced microservices architecture (RPC+SpringBoot+SpringCloud+Dubbo+K8s)

 

 

 

 

Vx: Yunduoa2019 or scan the following two-dimensional code to obtain it by yourself