Looking back on my 2021

As of this writing, the COVID-19 pandemic still persists. In Vietnam, people have just passed a horrible time of lockdown, we needed to stay at home for nearly 4 months. I have even got covid infected and spent a quarantine time for more than three weeks.

My balcony garden

Tech Lead at UMB Solution (ubitec)

Tech Lead was my official job title at ubitec. I have worked closely with two teams (7 developers in total) for developing two products ubichat and ubibot. My responsibilities were divided into three following roles:

- Software engineer: joined teams to implement/solve several challenging problems

- Technical consultant: for developers, Product Owners, Product Managers, and customers.

- Mentor: grew the teams in both technical skills and soft skills

Mental care

In my spare time, I enjoyed reading books and watching videos. I have been doing "meditation" in ... every moment in my life (no kidding 😊)

The following was my favorite 2021 Youtube channels:

- The Quoc Khanh Show Premium (TQKS Premium)

- Bar stories - Dustin On The Go

- Johnny Trí Nguyễn

Making life easier

This was a tough year due to COVID, however fortunately I could get my car driving license and buy a new house.

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Happy new year, 2022!

Comments

Math fundamentals and Katex

It was really tough for me to understand many articles about data science due to the requirements of understanding mathematics (especially linear algebra). I’ve started to gain some basic knowledges about Math by reading a book first. The great tool Typora and stackedit with supporting Katex syntax simply helps me to display Math-related symbols. Let’s start! The fundamental ideas of mathematics: “doing math” with numbers and functions. Linear algebra: “doing math” with vectors and linear transformations. 1. Solving equations Solving equations means finding the value of the unknown in the equation. To find the solution, we must break the problem down into simpler steps. E.g: x 2 − 4 = 4 5 x 2 − 4 + 4 = 4 5 + 4 x 2 = 4 9 x = 4 9 ∣ x ∣ = 7 x = 7 or x = − 7 \begin{aligned} x^2 - 4 &= 45\\ x^2 - 4 + 4 &= 45 + 4\\ x^2 &= 49\\ \sqrt{x}&=\sqrt{49}\\ |x| &= 7\\ x=7 &\text{ or } x=-7 \end{aligned} x 2 − 4 x 2 − 4 + 4 x 2 x ∣ x ∣ x = 7 = 4 5 = 4 ...

Styling Sort Icons Using Font Awesome for Primefaces' Data Table

So far, Primefaces has used image sprites for displaying the sort icons. This leads to a problem if we want to make a different style for these icons; for example, I would make the icon "arrow up" more blurry at the first time the table loading because I want to highlight the icon "arrow down". I found a way that I can replace these icons with Font Awesome icons. We will use "CSS Pseudo-classes" to achieve it. The hardest thing here is that we should handle displaying icons in different cases. There is a case both "arrow up" and "arrow down" showing and other case is only one of these icons is shown. .ui-sortable-column-icon.ui-icon.ui-icon-carat-2-n-s { background-image: none; margin-left: 5px; font-size: 1.1666em; position: relative; } .ui-sortable-column-icon.ui-icon.ui-icon-carat-2-n-s:not(.ui-icon-triangle-1-s)::before { content: "\f106"; font-family: "FontAwesome"; position: ...

Junit - Test fails on French or German string assertion

In my previous post about building a regex to check a text without special characters but allow German and French . I met a problem that the unit test works fine on my machine using Eclipse, but it was fail when running on Jenkins' build job. Here is my test: @Test public void shouldAllowFrenchAndGermanCharacters(){ String source = "ÄäÖöÜüß áÁàÀâÂéÉèÈêÊîÎçÇ"; assertFalse(SpecialCharactersUtils.isExistSpecialCharater(source)); } Production code: public static boolean isExistNotAllowedCharacters(String source){ Pattern regex = Pattern.compile("^[a-zA-Z_0-9_ÄäÖöÜüß áÁàÀâÂéÉèÈêÊîÎçÇ]*$"); Matcher matcher = regex.matcher(source); return !matcher.matches(); } The result likes the following: Failed tests: SpecialCharactersUtilsTest.shouldAllowFrenchAndGermanCharacters:32 null A guy from stackoverflow.com says: "This is probably due to the default encoding used for your Java source files. The ö in the string literal in the J...

When we don't see the sun, we see other stars

What are your motivations for creativity? - I want to make a change. - It makes me happy! It is a need of my mind. How to be creative for a thing? There are two steps: - See the thing as every people see it - Think about a new different thing from it How to think about a new different thing? There are two ways: - Forget all things you have already known. - A whack on the side of your head. ;) This was what I have learned from the following great book: source: Amazon.com Well! A physical whack on the side of your head is needed sometimes but the meaning behind is that you need to break these 9 following locks on your mind. Remove them! The lock #1: "The correct answer" We all learn from schools that there is only one correct answer to a question. For example, a proposition is only true or false in Algebra. In reality, there are always some answers to a question basing on a point of view. For example, number 6 becomes number 9 if you look it ...

Coding Exercise, Episode 1

I have received the following exercise from an interviewer, he didn't give the name of the problem. Honestly, I have no idea how to solve this problem even I have tried to read it three times before. Since I used to be a person who always tells myself "I am not the one good at algorithms", but giving up something too soon which I feel that I didn't spend enough effort to overcome is not my way. Then, I have sticked on it for 24 hours. According to the given image on the problem, I tried to get more clues by searching. Thanks to Google, I found a similar problem on Hackerrank (attached link below). My target here was trying my best to just understand the problem and was trying to solve it accordingly by the Editorial on Hackerrank. Due to this circumstance, it turns me to love solving algorithms from now on (laugh). Check it out! Problem You are given a very organized square of size N (1-based index) and a list of S commands The i th command will follow t...

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