[12.9-12.13] The Road to Technical Growth, Ali Interview, Book list, HashMap

The more you know, the more you don’t know

Review of this week’s selected articles:

Warm reminder: Click on the title to read

10 Years of Programming – From college to Technologist What did I do?

• Around these friends are in the field of the Internet for many years, because of life and personal habits, many do not have the habit of writing blog, or did not come out publicly, but they met Shuaic, I SAO ah, I can help them sort out ah.

  The purpose is to let a lot of new people like me have a clear understanding of a complete career planning road, what should bronze go through to the king?

  This article is written by me after I read the posts and asked the technical stack of each stage of learning and the depth and breadth of the technology to be achieved.

  Actually we found each stage to do ahead of the others, you need pay a lot of things, as a fresh graduates, I personally feel a little bit depth may be more important than your breadth, because you don’t know at this stage the future may contact technology stack, but you have to know about you already have a deep understanding and cognition, this will in school time you go out, It has certain core competitiveness.

  Again, knowing what it is, knowing why it is, you only use why should I want you over anyone else?

  As for my friends after work, I think the breadth of technology is your top priority at this stage. Breadth is actually very easy to expand, because that’s all the technology stack is.

  If the interviewer is particularly familiar with a technology stack, he must be deep into your technology stack. If you are not familiar with it, you may not be eliminated, but the probability of hiring you will be small.

  Breadth determines how far you can go, depth determines how high you can go, long programming road, Aobin with you.

Punch the Interviewer series -HashMap

• This is definitely the one that interviewers like to ask the most in the set, because it is very representative and its structure is more complex than other sets. You need to master almost all of its knowledge points to win this score firmly in the interview.

  HashMap

• The underlying data structure of HashMap?

• How does HashMap access work?

• What are the differences between Java7 and Java8?

• Why are threads unsafe?

• Are there any thread-safe classes instead?

• What is the default initialization size? Why so many? Why are the sizes always powers of 2?

• How to expand HashMap? What is the load factor? Why so many?

• What are the main parameters of a HashMap?

• How does a HashMap handle hash collisions?

• What are the rules for calculating hash?

  By the way, I will answer two small questions in the comments section, because most of you are probably confused

16 is a power of 2. 8 is a power of 2. 32 is a power of 2.

I think it’s just an empirical value, there’s no particular reason to define 16, as long as it’s a power of 2, it’s pretty much the same with 8 or 32.

16 is used only because the author thinks that the initial capacity of 16 is suitable for common use.

Lists in a Hashmap are automatically converted to a red-black tree when they are larger than eight, and become linked again when they are smaller than six.

According to the Poisson distribution, when the default load factor is 0.75, the probability that the number of elements in a single hash slot is 8 is less than one in a million. Therefore, 7 is regarded as a watershed, and the conversion is not performed when it is equal to 7, but when it is greater than or equal to 8, and when it is less than or equal to 6, it is transformed into a linked list.

Red-black trees will be written in the algorithm and data structure phase, but don’t worry, in HashMap it’s not 5,000 words.

Blood – a collection of top programmer books

• Wang Xiao: Pattern determines a person’s dream, and dream in turn determines behavior.

  So what’s the pattern?

  Pattern is the depth, breadth and density of what you can see.

  Wang Xiao believes that a book created the landscape. As she says, “Reading made me realize how big the world is, and then I opened the door to see the world.”

  In a previous article I wrote about almost the entire career of a tech person going from zero to one, and it turns out that there is no end.

  In fact, our whole life is basically learning, that mentioned learning, I think of the first time is reading.

  I remember that in the summer when Shuaibing was 21 years old, he got his first internship salary of 1400 yuan, because it was 110 yuan a day, and the first month on the job was not full, but he was still very happy. In the first month, his master gave him a suggestion: buy a book.

  In this way, I bought the first technical book after the society “Java Core Volume 1”, also recommended by the master, like a treasure.

  Up to now, my bookshelf is vast, but this book has always been with me, and it is also the most impressive technical book, because it feels like the taste of first love, sweet.

  Why do I recommend you to read books? The authors of books are years or even decades of experience, and finally summed up into a book. Even if there are mistakes in it, I think you can spend dozens of dollars, just a few weeks or even a few days to read the experience of more than ten years of others.

  As I said at the beginning of the article, my father often said that all inferior things are better than study. My family is also a family of teachers. When I was young, my grandfather was a teacher, and later my father, uncle and mother were all teachers without exception, but their salaries were too low and they all went out to work.

  But reading and education of other people’s day also gave them a lot of harvest, although dad is working, but he will often pondering and learning, also let me teach him baidu what, anyway I think he is still great, good reading yo.

An “encounter” between Ali and ME (Full explanation of the question)

• The content of this article is adapted from the real interview experience submitted by readers, the first time to try this style of article, it took a few nights to finally write, I hope to help you.

  It mainly covers the following contents:

1. Distributed mall system: architecture diagram explanation;

2. Message queue correlation: peak clipping and decoupling;

3. Redis related: cache penetration problem resolution;

4. Some basic questions:

5. – Network related:

   • What happens when the browser enters the URL?
   • Is TCP different from UDP?
   • How does TCP ensure transmission reliability?
   • Java basis:
   • Why have a character stream when you have a byte stream?
   • What’s the difference between a deep copy and a shallow copy?

   The interview process was full of ups and downs. True stories from Ali’s interviewees. Are ali’s interviewers always nice?

A hot Ant Financial service interview (has received the Offer)! Attached answer!!

• I still remember that I went to ant Financial for an interview when I was job-hopping in the middle of the year. To tell the truth, the difficulty of ant’s interview was quite impressive.

  Due to the high tension during the interview, the author listed only some questions that he could remember.

  After a long month of waiting, I was finally informed by the interviewer that I had been admitted by Ant Financial a few days ago. Needless to say, I felt anxious and painful during this period. When I was admitted, the haze of the whole year was swept away.

  The author is a Java R&D engineer of Ali, and the interview process is 3 rounds of technical interview +1 round of HR interview.

  The interviewer grilled the candidate about basics, multi-threading, memory, red-black trees, TCP/IP protocols, and so on. It’s not easy for most people to stand up to, but if you’ve watched the Aobin series and bought aobin’s service-building project, you might be on to something.

Obin’s ramblings

I wrote three high-quality original articles against each other this week. To be honest, I am already a little bit frustrated. Two of them require my full attention on Saturday and Sunday, and the third one requires working overtime on weekdays.

At the end of my affairs is really more, this week double 12 past, next week there are video shooting, the project at the end of the summary of what, next week blind guess three 100% pigeon, 2 I try my best, 1 guarantee.

I also wrote a summary of 2019. I paid off my student loans, left my job, moved to a new employer and started writing. Anyway, a lot of things.

Something meaningful

This week is not to draw books, people’s enthusiasm is a little beyond my imagination, the message directly hit full, but it seems that the suspense is not very big, can only say that the two friends are too strong, the book should be in their hands next week.

Did not draw the small partner do not be discouraged, at the end of the year I send 30 copies! Or random hahaha.

Next week’s notice

Next week’s article will have a 2019 summary, ConcurrentHashMap&Hashtable, and possibly ArrayList&LinkedList, but not sure if that will happen, so the last one is not guaranteed.

Weekend, everyone enjoy this weekend, wish everyone a good weekend.