A journey of a software engineer and computer science enthusiast
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Google I/O '18
Here are my top 5 impressions on this conference.
Gmail - live sentence suggestion
It looked like the way developers use intelligent code completion in an IDE when coding.
Google Photos: converting a photo has a document to pdf
I have a paid app on my iPad called "Scanner for Me" but now I can use Google Photos instead. ;)
Google Assistant: bot makes a real call to book a restaurant dinner or a hair salon
Wow! This feature, for me, is really a big innovation. My team is working so hard on building our bot which is able to have a continued conversation. Google is so good!
Google Maps: using Phone's camera to watch the direction
When I saw a fox as a cicerone on the demo, I was thinking of Pokémon GO.
Google Lens: extract text from images
I have heard a story from a friend of me that he had to use his app about "optical character recognition (OCR)" to scan and translate the texts into English whenever he saw texts in China. Google Lens would be a good helper for him now.
If you do Scrum at work, you might be very familiar to the estimation in Planning 1 . My PO has once complained to my team that why it took too long for estimating just a story. Wasting time results in the planning timebox is violated. I give you some advice from my experience: Estimation is estimation, not measure. When you read some requirements, you see some risks but you actually don't know how complicated it will be. Don't try to influence the others by explaining how to do it in too detail. Just keep in mind that you know the business domain pertaining to customer needs and estimate how much effort you will spend for it. The effort should be compared to your baseline one that you use for a simple requirement. The bottom line is we do "relative estimation", not absolute estimation. For example, you are asked to estimate the height of a building. Basically, you just need to answer "how many times higher is the build than your height"; you do...
Today, I was just curious about why an enum can not extend anything else. I took a look on the Oracle document here , and I found the answer is below: "All enums implicitly extend java.lang.Enum. Because a class can only extend one parent (see Declaring Classes), the Java language does not support multiple inheritance of state (see Multiple Inheritance of State, Implementation, and Type), and therefore an enum cannot extend anything else." I have been learned of it before. But, wait a sec...! Why Java does not support multiple inheritance of state? Since I have worked with other programming languages like C++, I was able to make a class extend some other classes. The short answer is to avoid the issues of multiple inheritance of state . I wonder if other programming languages have these below terms but Java does. Multiple inheritance of state It is the ability to inherit fields from multiple classes. There is a problem and Java avoids it. "For exa...
For example, I have a program with an Animal abstract class and two sub-classes Dog and Bird. I want to add new behavior for the class Animal, this is "fly". Now, I face two approaches to solve this issue: 1. Adding an abstract method "fly" into the class Animal. Then, I force the sub-classes should be implemented this method, something like: public abstract class Animal{ //bla bla public abstract void fly(); } public class Bird extends Animal{ //bla bla public void fly(){ System.out.println("Fly high"); } } public class Dog extends Animal{ //bla bla public void fly(){ System.out.println("Cant fly"); } } 2. Creating an interface with method "fly" inside. The same issue to an abstract class, I force the classes these implement this interface should have a method "fly" inside: public interface Flyable{ public void fly(); } public class Bird implements Flyable{ //bla bla public void fly(){ System.out.pr...
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 ...
"Creates a virtual table whose contents (columns and rows) are defined by a query. Use this statement to create a view of the data in one or more tables in the database. For example, a view can be used for the following purposes: - To focus, simplify, and customize the perception each user has of the database. - As a security mechanism by allowing users to access data through the view, without granting the users permissions to directly access the underlying base tables. - To provide a backward compatible interface to emulate a table whose schema has changed." [1] Beside that, our team used view in order to improve the performance of our web apps when a database has a very complicated relationship between its tables by using ORM Frameworks such as Hibernate. Example code: --create CREATE VIEW placeholders AS SELECT EMPKEY AS empkey, CONNUMB AS connumb, EMPNBR AS empNbr, ACEEMPN AS empFirstName, ACEEMPFN AS empLastName, EMPNAM AS empFullName, ...
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