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Performance of a Data Structure

Why data structures matter The fact is that programs are all about processing data. Data structures are referred to how data is organized which affects the time of executing a program.
How to measure the performance of a data structure In order to measure "how fast"/efficiency/performance of a data structure, we measure the performance of its operations. There are four basic operations including reading, searching, insertion, and deletion. A pure time consuming is not used for the measuring because it is not reliable depending on the hardware that it is run on. But instead, we use the term time complexity which refers to how many steps an operation takes.
An example of how a single rule can affect efficiency Let's compare two data structures: Array and Set (with N elements).
1. Array - Reading: 1 step (because the computer has the ability to jump to any particular index in the array)
- Searching: N steps (the worst case with linear search)
- Insertion: N + 1 steps (the wo…

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:
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 in the opposite.
The lock #2: "That is not logic&…

Fulfilling Your Contribution Needs

Human resource management motivation Managing human today is quite different from the industrial age which treats people as just "chickens". Rather than people now are very important to the success of an organization. People are an organization's special resource. They should be encouraged to grow to contribute their effort and creativeness to their beloved working environment because the contribution is one of their most needs in life.
Training people: getting rid of the ineffective model and adopting the new one The ineffective model of training people: Hiring new people --> giving them a crash course once --> expecting them working effectively. 

That somehow makes sense but you're about to expect a luck because you do not really spend your effort for mentoring them. If they can work effectively, well...lucky you! Otherwise, you will blame that these people are ineffective and you let them go and hire the new ones. What a waste of time!

The new effective one…

Daily Meetings - Coordinate and Communicate Every Day

Using daily meetings for frequent course corrections. However, you should keep the meeting short because time is burn rate.
Though good collaboration doesn't guarantee a project's success, poor collaboration almost always guarantees a project's failureWhat benefits does the daily meeting bring to you?

- Keeps inexperienced developers and experienced ones on-track.
- Avoids reinventing the wheel.
- Limits tumbleweed developers' damage.
- Leverages the entire team’s experience to solve problems quickly.
- Improves team communication.
- Helps every people have a big-picture
point of view.
Who are tumbleweed developers? We’ve all worked with a few tumbleweed developers. These developers lose direction and drift through their days. They wade through the random code and “improve” it, cleaning up method signatures, polishing algorithms, and reformatting brackets. Tumbleweed developers lack the discipline to finish any task you ask them to do and generally cause more harm th…

Trước Bình Minh Luôn Là Đêm Tối

This is a book telling about many stories of the book's author, Ta Minh Tuan. Each his story is not only a valuable lesson but also a heart-to-heart talk. Think Big, Start Small, Move Fast I accidentally attended a $2 meetup which was held by Hoithao.vn in 2013. It was the first time for me to see the author. At that time, he wanted the attendees to repeat many times a sentence "Think big, start small, move fast" (a mindset for entrepreneurs). It was really impressed to me. I've been following him on Facebook since 2013. This book was his recommendation. Do It Anyway Your success is defined by yourself. It is built by your habits. Habits are the things need time to tackle. To me, that somehow means JUST following your heart combining with your brain because you're the one who knows what you're doing. Believe in yourself and never betray your dream!
We Are One The author said that "everything is connected". This is also the theory of Buddha. He beli…

Java 8 - Persistent data structure

The following is a series of posts about "functional programming in Java" which is the result of my understanding by reading the book "Java 8 in Action: Lambdas, Streams, and Functional-style Programming, by Alan Mycroft and Mario Fusco".
1. Why functional programming?
2. Functional programming in Java 8
3. Java 8 - Using Functions as Values
4. Java 8 - Persistent data structure
Persistent data structure is also known as a simple technique but it's very important. Its other names are functional data structure and immutable data structure.
Why is it "persistent"? Their values persist and are isolated from changes happening elsewhere. That's it!
This technique is described as below:

If you need a data structure to represent the result of a computation, you should make a new one and not mutable an existing data structure.

Destructive updates version
public static A doSomething(A a){ a.setProp1("new value"); return a; }
Functional versi…

Java 8 - Using Functions as Values

The following is a series of posts about "functional programming in Java" which is the result of my understanding by reading the book "Java 8 in Action: Lambdas, Streams, and Functional-style Programming, by Alan Mycroft and Mario Fusco".
1. Why functional programming?
2. Functional programming in Java 8
3. Java 8 - Using Functions as Values
4. Java 8 - Persistent data structure
In general, the phrase "functional-style programming" means the behavior of functions should be like that of mathematical-style functions - no side effects.

In programmers' point of views, functions may be used like other values: passed as arguments, returned as result, and stored in data structures. That means we can use the :: operator to create a method reference, and lambda expressions to directly express function values. For example:
//method reference Function<String, Integer> strToInt = Integer::parseInt; //lambda expression Comparator<Integer> comparator =…

Small Changes to Java 7 via Project Coin and Why They are Useful

Did you know how new features were added into Java 7? The following are functionalities that can be considered.
Source: [1] Project Coin is all about the changes in the range from syntactic sugar to new language feature. This is what we're talking about today.

Since Java 7 is the first version developed in an open source manner, there is an amount of actions that must be performed for any changes as follows:
Update the Java Language Specification (JSL)Implement a prototype in the source compilerAdd library support essential for the changeWrite tests and examplesUpdate documentEtc, ... Project Coin has submitted a lot of proposals (almost 70) but only some of them are chosen to Java 7. Why? Briefly, Java is a rich static type system and it has a lot of possible interaction points between different bits of it. Making changes to this type system is prone to creating unexpected surprises.

Wow! It is tough, right? Let's take a look what features Project Coin brought to Java 7.
Strings…

Review - The Object-Oriented Thought Process, by Matt Weisfeld

In this post, I would like to point out what I understood after closing my eyes and thinking about what  exactly I have learned from this book. That means the layout of content does not follow the book.
From Procedural to Object Oriented Once upon a time, there is an issue that it is very hard to test and debug in Procedural programming because the data is sometimes global and can be modified by multiple functions.

Object-Oriented (OO) programming addresses these problems by combining both data and functions into an object. That means only functions belong to the object can access its own data.

Let us check the below two different approaches for a case that we want to transfer information between clients and servers across a network.

-    Procedural programming: a client (browser) transfers a JSON data to a server which needs to know how to process with this data. In order words, a handshaking agreement must be defined for the client and server in order to work together.
-    OO prog…

Meaningful Names - Code Review Checklist with Example

"Names are everywhere in software". "The hardest thing about choosing good names is that it requires good descriptive skills"[1]. In my previous post, I emphasized that we should take care our code, so now let's start with naming.

Issue Original code Revised code Reveals nothing int d; //elapsed time in days int elapsedTimeInDays; Difficult to understand public List<Cell> getThem()
public List<Cell> getFlaggedCells()
Specific to programmers accountList accounts

If We Want to Go Fast, We Need to Go Well

Have you ever thought that we won't need to code anymore because programs might be generated from specification? The answer can be yes or no; there is still arguing about it.

The programming language is more and more closed to the requirements. The starting is from a very low level as Assembly to a very high level like Python. However, it doesn't make much sense when saying that we will eliminate coding. For me, we currently still need to express our ideas in exact words that tells the machine what we want. Otherwise, I hope in the future the machine is intelligent enough to understand our requirements directly from our words. ;)

Take a look at the famous quote of Robert C.Martin about what I mentioned above:

"Remember that code is really the language in which we ultimately express the requirements. We may create languages that are closer to the requirements. We may create tools that help us parse and assemble those requirements into formal structures. But we will never e…

Software Craftsmanship by Sandro Mancuso

Source: http://www.goodreads.com/book/show/18054154-software-craftsmanship
My first time to know about the term "Software Craftsmanship" is from Agile Tour Vietnam 2015. I finally read this book written by Sandro Mancuso who I met at this event.

Software Craftsmanship is a metaphor for software development: software as a craft and developers as blacksmiths. In other words, Software Craftsmanship is about professionalism in software development.

The Software Craftsmanship manifesto:
Not only working software, but also well-crafted software: regardless how old the application is, developers can understand it easily; high an reliable test coverage, clear and simple design, business language well expressed in the code.Not only responding to change, but also steadily adding value: constantly improving the structure of the code, keeping it clean, extendable, testable, and easy to maintain; always leave the code cleaner than we found it.Not only individuals and interactions, but al…