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  Is Java Set ordered or not?

“Is Java Set ordered or not? ” is the most popular question asked when you interview for a Java Developer position. Many fail to answer it, and I have to admit I was one of the many. I have known the answer is “Yes and No” for a long time. No. HashSet is not ordered. Yes.TreeSet is ordered. If the interviewer continues with some follow up questions, I’m not confident that I know the answer then. Why is TreeSet ordered? Are there any other ordered S...

   ORDER,SORTEDSET,HASHSET,JAVA     2021-02-11 06:55:00

  Why do I need a debugger?

  When I begin to learn a new programming language, I will try and master the debugger for it as early as possible. For example, in 2013, while I touched the Go, there seems only gdb for use. Although gdb itself is not a good choice (From Debugging Go Code with GDB): As a consequence, although GDB can be useful in some situations, it is not a reliable debugger for Go programs, particularly heavily concurrent ones. But at that time there was no other choice. So after delve&nb...

       2017-07-21 22:53:16

  How small should a function be?

"The well-designed functions are often relatively small, large function design is often a mess or there is a lot of room for optimization."Maybe you think there is no need to discuss the size of functions, because the nature of the function design is cohesive, its size is only its manifestations. But it is necessary to discuss about the size of function because the statement above .First let's understand the concept of minimum code processing unit : a basic operation (assignment, comparison, etc...

   Function size,Optimization     2012-12-18 13:58:07

  Be cautious before deciding to use ReactJS in your product

ReactJS is an open source JavaScript library used for writing user interfaces. It revamps the way developers write web applications. More and more front end developers start to use this Facebook crafted library in their products or projects nowadays. However, although ReactJS is an open source library under BSD license, it doesn't mean there is no risk to freely adopts it in your products. If you are building or plain to build some products which may compete with Facebook or its subsid...

   JAVASCRIPT,FACEBOOK,REACTJS,VUE     2016-07-16 20:43:16

  Recover deleted file in Linux EXT3 file system

Environment : CentOS 5.3 x86_64, /dev/sdb1 is the data segment /data0. EXT3 file system. Problem : /data0/tcsql/cankao/phpcws-1.5.0/httpcws.cpp is deleted mistakenly and httpcws.cpp is not backed up. It will take much time to rewrite this program again. So we must recover it back. debugfs is feasible in EXT2 file system, but in EXT3 file system, it's not very useful. There is one open source software called ext3grep which can help us recover deleted file in EXT3 file system. The recovery steps a...

   Linux,EXT3,File recovery     2013-08-16 07:06:45

  Go Lacks Ternary Operators. Here Are Some Equivalents

If you were like me, a pure Java developer before writing Go, you must be wondering why Go doesn’t support the ternary operator like return a > 1 ? 0 : 1. Most mainstream languages like C and Java are supportive of ternary operators; languages like Python and Ruby support the simplified if-else one-liner, such as a = 0 if a > 1. However, Go is not among them. And it is not only about adding operators but also a concept of coding in a more convenient way, such as the ?: expression can...

   GOLANG,TERNARY OPERATOR     2022-12-09 19:51:32

  Tips of Drafting an R Markdown Document

When presenting the data summary and exploratory analysis, we used to copy a lot of tables, charts from Rstudio to PowerPoint, which makes the presentation preparation painful. It becomes essential for data scientists to make use of better reporting tools, such as R markdown, Jupyter notebook to prepare the analysis presentation in a more efficient and organized way. Of course, we want this to be reproducible! In this post, I would like to share some tips of using the right tools to draw tables,...

   R PROGRAMMING     2020-11-01 23:09:45

  Cool HTML5 matrix effect

Do you still remember the movie The Matrix? Do you still remember the cool matrix effect in that movie? How is that effect achieved? Shaun Dunne shared a piece of HTML5 code which displays a cool matrix effect. The matrix demo can be found here. Below is the code which he achieves this effect: with var s = window.screen; var width = q.width = s.width; var height = q.height = s.height; var letters = Array(256).join(1).split(''); var draw = function () { q.getContext('2d').fillStyle='rgba(0,0,...

   Matrix,HTML5     2013-08-14 08:03:34

  The tic-tac-toe game with Python

In this tutorial, we will show how to build a tic-tac-toe game with Python. We will use functions,arrays,if statements,while statements, for loops and error handling etc. First, we need to create two functions, the first function will display the borad of the game: def print_board(): for i in range(0,3): for j in range(0,3): print map[2-i][j], if j != 2: print "|", print "" Here we used two for loops to loop through the map, this map is...

   Python,Tic-Tac-Toe     2013-07-30 02:49:09

  About C++ comma operator precedence

When learning programming language, we will always have one topic about the operator precedence. Since there are many operators can be used in one expression, there should be some rules regarding which operation can happen first so that the compiler or interpreter can handle them correctly. One rule of programming with expression is using as much as brackets as you can to avoid unexpected results. Here we refer one problem we see online about the comma operator in C++. The following program has ...

   comma,precedence     2012-11-12 10:25:00

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