Cow breaking! The latest "Basic-Intermediate-Advanced" Java programmer interview assembly in 2021, give my knees after reading

Java basics (object + thread + character + interface + variable + exception + method)

1. What is the difference between object-oriented and process-oriented?
2. What are the characteristics of the Java language?
3. The most detailed and popular answer about JVM JDK and JRE
4. Comparison of Oracle JDK and OpenJDK
5. What is the difference between Java and C++?
6. What is the main class of a Java program? What is the difference between the main class of application and applet?
7. What are the differences between Java applications and applets?
8. The difference between character constants and string constants
9. Can Constructor be overridden?
10. The difference between overloading and rewriting?
11. Three characteristics of Java object-oriented programming: encapsulation inheritance polymorphism
12. What is the difference between String StringBuffer and StringBuilder? Why is String immutable?
13. Automatic boxing and unboxing
14. Why is it illegal to call a non-static member in a static method?
15. What is the purpose of defining a constructor that does nothing and has no parameters in Java?
16. What is the difference between import java and javax?
17. What is the difference between an interface and an abstract class?
18. What are the differences between member variables and local variables?
19. What operator is used to create an object? What is the difference between an object entity and an object reference?
20. What is the return value of the method? What is the function of the return value in the method of the class?
21. What is the role of a class's constructor? If a class does not declare a constructor, can the program be executed correctly? Why?
22. What are the characteristics of the construction method?
23. What is the difference between static methods and instance methods?
24. What is the difference between the equality of objects and the equality of references to them?
25. Before calling the subclass construction method, the parent class construction method without parameters will be called first. What is the purpose?
26. == and equals (important)
27. hashCode and equals (important)
28. Why is there only value passing in Java?
29. Briefly describe the basic concepts of threads, programs, and processes. And what is the relationship between them
30. What are the basic states of threads?
31. Some summary on final keywords
32. Exception handling in Java
33. What if some fields do not want to be serialized in Java serialization?
34. Two commonly used methods for obtaining keyboard input?

Regarding the topic of Java basics, I only listed 34 more representative ones. The topic is here, and the corresponding answers are also there, but the answers are more than 20 pages (organized into PDF), and an article here cannot be used. Show all (take a few pictures to see below), and there are interview questions for intermediate developers + senior programmers below. , Friends in need, click here to get it for free!

Answers to the Java Basic Interview Part

Answers to the Java Basic Interview Part

Intermediate Java development (bottom layer + Spring related + Redis + distributed + design mode + MySQL + high concurrency + lock + thread)

1. HashMap underlying implementation principle, red-black tree, B+ tree, B-tree structure principle, volatile keyword, CAS (comparison and exchange) realization principle
2. What are Spring's AOP and IOC? What are the usage scenarios? Spring transaction, transaction attributes, propagation behavior, database isolation level
3. What are the annotations of Spring and SpringMVC, MyBatis and SpringBoot? The working principle of SpringMVC, the advantages of SpringBoot framework, the advantages of MyBatis framework
4. What are the SpringCould components and what are their functions? (Say seven or eight) What is the CAP of microservices? What is BASE?
5. Design patterns (say five or six)
6. Data types and usage scenarios supported by Redis, persistence, sentinel mechanism, cache breakdown, cache penetration
7. What is a thread, there are several implementation methods, what is the difference between them, the principle of thread pool implementation, JUC concurrent package, the difference between ThreadLocal and Lock and Synchronize?
8. Distributed transaction (how to ensure data consistency between different systems (system A writes data, system B does not write successfully for some reasons, resulting in data inconsistency))
9. Security issues (data tampering (getting someone else’s URL, tampering with the data (amount) sent to the system))
10. Restrictions on the use of indexes, what are the sql optimizations, and data synchronization issues (cache, database data synchronization)
11. There are several steps to initialize a Bean object, its life cycle
12. JVM memory model, algorithm, garbage collector, tuning, class loading mechanism (parent delegation), create an object, how is this object allocated in memory?
13. How to design a spike system? (High concurrency and high availability distributed cluster)
14. What are pessimistic locks, optimistic locks, read-write locks, row locks, table locks, spin locks, deadlocks, distributed locks, thread synchronization locks, fair locks, and unfair locks?
15. Heap overflow, stack overflow scenarios and solutions
16. Tell the difference between several types of MQ, and why this MQ is used, the message is sent repeatedly (idempotence), the message transmission fails, the message packet is dropped, the message is not received for a long time, and the message sent is too large, resulting in unsuccessful reception
17. Single sign-on implementation principle
18. If there are hundreds of millions of data, how do you quickly find one of the data you want (several simple algorithms)
19. The operating principle of Dubbo, what protocols it supports, why is it more efficient than SpringCould, and the underlying principle of Zookeeper
20. If you lead a team to design a system, what do you need to consider?

Intermediate Java development, the questions listed above are about the same. The answers are more than 40 pages in PDF. The length is not good. All the answers are attached. I intercept some of the answers and show them. More complete answers, no matter the basic part or Both intermediate and advanced levels are available, click here to get it for free!

Java Intermediate Development Part Answer

Java Intermediate Development Part Answer

Java advanced "programme" (high concurrency + Redis cache + distributed + message queue + high availability + micro service + sub-database and table + read-write separation)

1. High Concurrency (Classic Interview Question: How to Design a High Concurrency System?)

How to design a high concurrency system?

1. Redis cache

 

1. distributed

 

 

1. message queue

 

 

1. High availability

 

 

 

1. Microservice

 

1. Sub-database and sub-table

 

1. Read and write separation

 

In the Java advanced "programming" interview part (the title has been marked with a red box), I have a total of 8 parts, including high concurrency, Redis caching, distributed, message queue, high availability, microservices, sub-database sub-table, reading Write separation, etc., and each topic in each part has a corresponding interviewer psychoanalysis and interview topic analysis, so that we can clearly understand where the focus of the topic is at this time and where to tackle it during the interview!

There is a lot of content in this part. After sorting out the entire question and answer , there is a 180-page PDF . It is even more impossible to attach all the answers. Here we only show part of the answer analysis. The full PDF is available for free here!

Answers to the Java Advanced "Program Apes" Interview Part

Answers to the Java Advanced "Program Apes" Interview Part

Finally I want to say...

Whether it is basic, intermediate, or advanced, each part is very important, and I think it is especially basic. If the foundation is not solid, how to build a building?
And all of the basic interview questions, the corresponding questions for intermediate development, and the knowledge points that senior programmers need to master, all the relevant complete analyses have been sorted out. There are more than 40 pages of questions + answers for the basic part, and more than 40 pages for the intermediate development. The content of the advanced part is more (there are 180 pages), all of which are made into PDF files. Friends in need come to the editor to receive That's it. Click here to get it for free!