Java basics (object + thread + character + interface + variable + exception + method)
- What is the difference between object-oriented and process-oriented?
- What are the characteristics of the Java language?
- The most detailed and popular answers about JVM JDK and JRE
- Comparison of Oracle JDK and OpenJDK
- Difference between Java and C++?
- What is the main class of a Java program? What is the difference between the main class of an application and an applet?
- What are the differences between Java applications and applets?
- The difference between character constants and string constants
- Can the constructor Constructor be overridden?
- What is the difference between overloading and overriding?
- Three major features of Java object-oriented programming: encapsulation inheritance polymorphism
- What is the difference between String StringBuffer and StringBuilder? Why is String immutable?
- Automatic boxing and unboxing
- Why is it illegal to call a non-static member inside a static method?
- What is the effect of defining a constructor that does nothing and takes no parameters in Java?
- What is the difference between import java and javax?
- What is the difference between interface and abstract class?
- What is the difference between member variables and local variables?
- What operator is used to create an object? How is an object entity different from an object reference?
- What is the return value of a method? What is the function of the return value in the method of the class?
- What is the function of the construction method of a class? If a class does not declare a construction method, can the program be executed correctly? Why?
- What are the characteristics of the constructor?
- How are static methods different from instance methods?
- What is the difference between the equality of objects and the equality of references to them?
- Before calling the constructor of the subclass, the constructor of the parent class without parameters will be called first. What is the purpose?
- == and equals (important)
- hashCode and equals (important)
- Why is there only pass by value in Java?
- Briefly describe the basic concepts of threads, programs, and processes. and what is the relationship between them
- What are the basic states of a thread?
- Some conclusions about the final keyword
- Exception handling in Java
- What if some fields do not want to be serialized in Java serialization?
- Get the two methods commonly used for typing with the keyboard?
I have only listed 34 representative questions about the basics of Java. The questions are here, and the corresponding answers are also there, but the answers have more than 20 pages (organized into PDF). Show them all (take a few screenshots to see), and there are interview questions for intermediate development + senior programmers below.
Java basic interview partial answer
Java basic interview partial answer
Java intermediate development (bottom + Spring related + Redis + distributed + design mode + MySQL + high concurrency + lock + thread)
- The underlying implementation principle of HashMap, red-black tree, B+ tree, structure principle of B tree, volatile keyword, CAS (comparison and exchange) implementation principle
- What are Spring's AOP and IOC? What are the usage scenarios? Spring transactions, transaction attributes, propagation behavior, database isolation level
- What are the annotations of Spring and SpringMVC, MyBatis and SpringBoot? The working principle of SpringMVC, the advantages of the SpringBoot framework, the advantages of the MyBatis framework
- What are the SpringCould components and what are their functions? (Say seven or eight) What is the CAP of microservices? What is BASE?
- Design pattern (say five or six)
- Data types supported by Redis and usage scenarios, persistence, sentinel mechanism, cache breakdown, cache penetration
- 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?
- Distributed transactions (how to ensure data consistency between different systems (system A writes data, system B fails to write for some reason, resulting in data inconsistency))
- Security issues (data tampering (get someone else's URL, tamper with data (amount) and send it to the system))
- Restrictions on the use of indexes, what are the sql optimizations, data synchronization issues (cache, database data synchronization)
- There are several steps to initialize the Bean object, its life cycle
- JVM memory model, algorithm, garbage collector, tuning, class loading mechanism (parent delegation), creating an object, how is this object allocated in memory?
- How to design a seckill system? (High concurrency and high availability distributed cluster)
- 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?
- Heap overflow, occurrence scenarios and solutions of stack overflow
- Tell the difference between several kinds of MQ, and why use this kind of MQ, the message is sent repeatedly (idempotency), the message fails to be sent, the message is dropped, the message cannot be received for a long time, and the sent message is too large to cause unsuccessful reception
- Single sign-on implementation principle
- If there are hundreds of millions of data, how do you quickly find one of the data you want (several simple algorithms)
- The operating principle of Dubbo, what protocols are supported, why it is more efficient than SpringCould, and the underlying principles of Zookeeper
- If you lead a team and ask you to design a system, what do you need to consider?
For Java intermediate development, the questions listed above are roughly like this. I have compiled the answers into PDF with dozens of pages. The space is not good enough to attach all the answers. Take a part of the answers and show them. More complete answers, whether it is the basic part or Both intermediate and advanced levels can be downloaded from the editor for free, just private message me to "learn"!
Java Intermediate Development Partial Answers
Java Intermediate Development Partial Answers
Java advanced "programmer" (high concurrency + Redis cache + distributed + message queue + high availability + microservices + sub-database and sub-table + read-write separation)
- High concurrency (classic interview question: how to design a high concurrency system?)
How to design a high concurrent system?
- Redis cache
- distributed
- message queue
- high availability
- microservice
- Sub-library and sub-table
- read-write separation
Java advanced "programmer" interview part (the topic has been marked with a red frame), I have a total of 8 parts, including high concurrency, Redis cache, distributed, message queue, high availability, microservices, sub-database sub-table, read Writing separation, etc., and each topic of each part has a corresponding interviewer's psychological analysis and interview topic analysis, so that we can clearly understand where the focus of the topic is at this time during the interview, and where to start to overcome it!
There is a lot of content in this part. The entire question + answer has been sorted out and there are hundreds of pages of PDF together . It is even more impossible to attach all the answers. Here we only show part of the answer analysis. The complete PDF can be directly sent to private message I "learn" to get it for free!
Part of the Java senior "programmer" interview answers
Part of the Java senior "programmer" interview answers
Finally I want to say...
Whether it is basic, intermediate or advanced, each part is very important, and I think especially the basic part, if the foundation is not solid, how to build a building?
And all the basic part of the interview questions I have listed above, the corresponding questions for intermediate development, and the knowledge points that senior programmers need to master, and the relevant complete analysis are all sorted out. There are more than 40 pages of questions + answers for the basic part, more than 40 pages for intermediate development, and more content for the advanced part (180 pages), all of which have been made into PDF files. Friends in need can come to the editor to collect That's fine.
But remember to private message me to "study", and the editor will immediately reply to you how to download the original PDF of the complete analysis answer !