preface

If you are not completely sure of yourself or your Java proficiency, this can be a very tricky problem. If this is the case, you should mark it down a bit. Later, you’ll probably get questions that match your level of admission. So if you give yourself full marks and can’t answer a difficult question, that’s going to hurt you. Today I will share these things to partners, but also for partners to save a lot of trouble, want to learn what skills, which aspects of the problem directly open the document to learn. No more talking, go straight to the dry stuff!

High tech interview questions

Here are some of the Java backend technologies that large companies need to use, and here is a special organized document that I hope you can have a look. These topics are technical and require a lot of time to study. Full version Java interview questions address: Java backend questions integration

(1) Network and security mechanism

(1) network framework comparison and source analysis (2) to design their own network request framework, how to do? Okhttp source code (3) network request cache processing, okHTTP how to handle network cache (4) load a 10M image from the network, (5) TCP three-way handshake and four-way handshake (6) TCP and UDP differences (7) TCP and UDP applications (8) HTTP protocol (9) HTTP1.0 and 2.0 differences (10) HTTP packet structure (11) HTTP and HTTPS differences and how to achieve security (12) How to verify the validity of the certificate? (13) Where is symmetric encryption used in HTTPS? Where is asymmetric encryption used? Do you know encryption algorithms (such as RSA)? (14) How does the client ensure that the message it sends is received by the server? (16) WebSocket and socket difference (17) talk about your understanding of android signature. (18) Please explain why Android adds signature mechanism? (19) Video encryption transmission (11) How does App sandbox and why do it? (12) Permission management system (how does the underlying permission grant?)

(2) Database

(1) SQLite upgrade, add field statement (2) database framework comparison and source code analysis (3) database optimization (4) database data migration problems

(3) algorithm

(1) What are the sorting algorithms? (2) Which is the fastest sorting algorithm? (3) write a bubble sort (4) write a quick sort code (5) quick sort, time complexity and space complexity of the process (6) write a heap heap sort (7) sorting process, time complexity and space complexity (8) to write what you know sorting algorithm and the complexity of time and space, stability (9) binary tree root node and destination node, Find the path from the root node to the target node (10) Which algorithm should be selected to rank ali’s more than 20,000 employees according to their ages? (11) GC algorithm (advantages and disadvantages of various algorithms and application scenarios) ant colony algorithm and Monte Carlo method string inclusion problem (KMP algorithm) write code to achieve an unordered, non-repeating array, output N elements, make the sum of N elements M, give time complexity, space complexity. Handwritten algorithm trillion level of two URL files A and B, how to find the difference between A and B C(hint: Bit mapping -> Hash grouping -> multi-file read and write efficiency -> disk addressing and application layer facing addressing optimization) Baidu POI how to try to find the latest business function (hint: coordinate mirror +R tree). Find the common element of two sets of non-repeating arrays.

(12) In two non-repeating array sets, these two sets are massive data, not fit in memory, how to find common elements? There are 1 million integers in a file, separated by space, in the program to judge whether the integer user input is in this file. What is the best way to calculate the memory footprint of a Bitmap and the memory footprint of 20 million integers? It takes a total of 1 hour to burn an uneven rope from head to tail. Now there are several rope of the same material, how to use the method of burning rope to time an hour and fifteen minutes? Find the number of daffodils up to 1000 and the number of daffodils up to 4 billion 5 coins, 2 heads and 3 tails how to divide into two piles and then by flipping the two piles of hard 8 coins heads up and tails up the same number of coins go round the hour hand, how many times the hour hand overlap N by N square paper, how many squares x apples are there, One, two, or three per day. How many days?

(4) Architectural design and design mode

(1) Talk about your understanding of Java design patterns (2) MVC MVP MVVM principles and differences (3) What design patterns do you know? (4) Common design patterns used in projects (5) Handwritten producer/consumer pattern (6) Write code for observer pattern (7) Adapter pattern, decorator pattern, appearance pattern similarities and differences? (8) the use of some open source framework, introduced a read source code, internal implementation process. (10) RxJava functions and principles of implementation (11) RxJava functions, compared with the advantages and disadvantages of ordinary use of asynchronous operation (12) Talk about the functions of EventBus, implementation method, instead of EventBus (13) design an App from 0 to the overall architecture. How to do it? (14) Describe a popular application (e.g. live streaming APP, P2P finance, small video, etc.) and design it. (15) Talk about the understanding of Java state machine. (17) Binder mechanisms and underlying implementations (18) What about application updates? (Answer: grayscale, forced update, sub-region update)? (19) Implement a Json parser (speed can be increased by re) (20) statistics startup time, standard

(v) Performance optimization

(1) How to analyze and optimize the performance of Java applications? (2) DDMS and traceView (3) How to analyze systrace performance optimization? (4) How to analyze memory leaks with IDE? (5) How to solve the performance problem caused by Java multi-threading? (6) White screen and black screen on the startup page? (7) How to solve the problem of starting too slowly? (8) How to ensure that the application starts smoothly? (9) App startup crash exception capture (10) Custom View notes (11) Now *** is very slow, try to analyze the reason from the perspective of network protocol, and optimize (tip: the network of 5 layers can be involved). (12) Https request slow solution (hint: DNS, which carries data, Direct access IP) (13) how to maintain the stability of the application (14) RecyclerView and ListView performance comparison (15) ListView optimization (16) RecycleView optimization (17) View rendering (18) Bitmap how to deal with the big picture, For example, a 30M large map, how to prevent OOM (19) Java four kinds of reference difference and use scenario (20) strong reference set null, will not be recycled? (21) non-technical problems & HR summary (22) is finishing some have no direct relationship with the technical interview questions, but to be able to review the comprehensive level of you, so don’t think that is not a technical problem, just don’t see, sometimes is it some of the detail of the subject is often neglected, but missed again and again the interview chance.

(1) Non-technical issues

(1) What projects have you worked on? (1) What frameworks and platforms have you used? (2) Which custom controls have you used? (3) What are the in-depth research fields? (4) What are the channels of attention to industry information? (5) What books have you read recently? (6) Are there any open source projects? (8) What open source libraries are used in the project and how to avoid security and stability problems caused by the introduction of open source libraries? (9) What did I do during the internship and what was the output?

(2) Interview questions raised by HR

(1) Why did you leave your previous company? (2) Tell me one thing that impresses you the most (3) introduce a project that has influenced you the most (4) Introduce your favorite field of expertise (5) What is the biggest gain from the internship in the company? (6) What will you do when you disagree with your superiors? (7) What are your strengths and weaknesses? And give some examples? (8) What is your learning method? How do you learn during the internship? What was the biggest difficulty you encountered in the internship program and how did you solve it? What would you do if you were hired by our company after this interview, but after some time of working, you found that you are not suitable for the position at all? What would you do? (12) What was the biggest difficulty in the project? How is it solved? (13) Your career plan and personal goals, future development path and job positioning (14) What will you do if you are not hired in this interview? (15) Evaluate yourself, evaluate your technical level, how much personal code? (16) What channels did you learn about the recruitment information and which companies did other students invest in? (17) What are your hobbies in your spare time? (18) What are you most proud of having done? What would you do if you had to see a classmate who is going abroad to the airport? (20) What do you think you lack for the position you are applying for? (21) Current offer status; If BATH gave offer how to choose? (22) What do you value more in a job? Platform, technology, atmosphere, city, or money? (23) Ideal salary range; Which hangzhou post and Beijing post choose? (24) What is the ideal work environment? What can you learn from your colleagues/classmates during the internship? (28) Your Family’s Expectations and your own (29) What do you think will happen if something goes wrong in your work and this company suffers financial losses? (30) What should I do if my boss misunderstands you in a public meeting? (31) Can I practice and for how long? Where would you like to see your career in five years time what do you see in this company Or what aspects of the company appeal to you most?

The last

Recently in view of the Internet company interview asked knowledge points, summed up the Java programmer interview involves most of the interview questions and answers to share with you, I hope to help you review before the interview and find a good job, but also save you on the Internet to search for information time to learn. Through my painstaking sorting out of the interview materials I hope everyone can interview on their favorite company!!

Content covers: Java, MyBatis, ZooKeeper, Dubbo, Elasticsearch, Memcached, Redis, MySQL, Spring, SpringBoot, SpringCloud, RabbitMQ, Kafka, Linux and other technology stacks.

Full Version of the Java InterviewJAVA backend test integration