SEARCH KEYWORD -- class initialization


  Understanding abstract interface in Java

Have you read about an interface declaration as public abstract interface InterfaceName in Java? At the first glance, is it a weird declaration? Why should we declare an interface as abstract? For example, we may see below code in some projects: public abstract interface MyInterface { public void check(); public abstract boolean check(boolean really); } Actually here abstract is redundant, an interface is implicitly abstract, we no need to put an abstract in front of interface. But it do...

   Java,abstract interface     2014-08-18 23:07:27

  Will nil == nil be true in GoLang

There is some interview question may ask whether nil == nil be true in GoLang. Wil it be true. false or compilation error? To know the answer, some knowledge about nil in GoLang needs to be explained first. nil definition According to Go's official documentation, the definition of nil is // nil is a predeclared identifier representing the zero value for a // pointer, channel, func, interface, map, or slice type. var nil Type // Type must be a pointer, channel, func, interface, map, or slice type...

   GOLANG,NIL,NIL EXPLANATION     2021-08-08 02:54:15

  What do programmers like to say usually?

Coding is an very important part of programmer's daily work. But beyond coding, programmers need to do other work as well, they need to fix bugs reported by users, they need to write documents for their codes. Also, they often need to answer questions from customers, bosses and colleagues. What do they often say when they are facing different sort of questions? Today we share some. It's done. I just need to clean up a few things. This is hacky, but I'll fix it soon. This can never happen: It's ...

   Programmer,Execuse,Bug     2013-08-07 07:38:30

  Speech balloon with pure CSS--One step further

Many of us want to add cool features to our websites to make our websites user friendly ad more attractive. Especially in Web2.0 era. Today we are talking about adding speech balloon feature to our webpage so that we can display beautiful help windows while users mouse over some help icons on our page. First, let me introduce one post written by Umar Ashfaq named "How to create a speech balloon with pure CSS". He also explains how this works. You can also refer Magic CSS shape for more informati...

   Speech balloon, Pure CSS,border     2013-03-16 04:11:58

  Understanding Slice Behavior in Go

In Go, understanding how slices behave when passed to functions is crucial for writing efficient and bug-free code. This behavior is often a source of confusion for many developers, especially those new to the language. In this article, we'll explore the difference between passing slices by value and by reference, and how it impacts the modification of slices within functions. Introduction In Go, slices are a fundamental data structure used to work with sequences of elements. They are essentiall...

   PASS BY REFERENCE,ARRAY,SLICE,PASS BY VALUE     2024-03-10 06:43:51

  Save QWidget as image

Qt library is an excellent GUI library for C++ programmers developed by Nokia and now is an open source project. Often, we may use QPainter to draw strings, lines or images on a QWidget. We can override the QWidget's paintEvent() method when we want to use QPianter object to draw something on a QWidget. If we want to save the items drawn on QWidget as image for later reference, what can we do? We can save a QWidget as an image. Here is the code for achieving this: QPixmap pixmap(this->size())...

   Qt,C++,QWidget,Image     2012-08-19 12:01:18

  Will Google+ be a "Ghost City"

Just now, I read an article about Google+’s status quo. The key point of this article is that it states that Google+ is now a “Ghost City”. According to the article, users of Google+ spend only 3 minutes per month on Google+, this is a very low participation rate for a social network website. After reading this, I wonder whether Google+ is really a Ghost City now, I cannot give my answer. Since it was released just around 8 months ago, so the user base is not very large. ...

   Google+,Social fayigue,User base,Ghost City     2012-02-28 09:44:39

  Reproduce "MySQL server has gone away" in PHP

If you want to debug the issue of "MySQL server has gone away", you can reproduce it with below steps: Modify configuration file: sudo vi /etc/mysql/my.cnf  Make below changes: [mysqld]   wait_timeout = 30   interactive_timeout = 30  Restart the service: sudo /etc/init.d/mysql restart  Write below PHP codes: $link = mysql_connect('127.0.0.1', 'root', 'root');   if (!$link)&nbs...

   MySQL,debug,rMySQL server has gone away     2013-04-15 11:33:14

  Signature sign/verification demo in Java

Digital signature is commonly used in areas where data authentication and integrity are required. It is extremely important to have signature while transferring sensitive data from one peer to other peers through network since there might be malicious applications or man-in-the-middle attacks which may alter the data along the way. Java provides some APIs to generate and verify digital signature. One important class is Signature.  When generating the signature, a private key needs to be pa...

   SECURITY,JAVA,SIGNATURE     2015-11-21 09:48:12

  Why using + to concatenate string in Java loop is not a good option

String concatenation is a common operation in Java programming. It is to concatenate multiple strings into a single string. Java provides a String class which is an immutable class which means the object cannot be mutated once instantiated. Once a String object is instantiated, its properties cannot be changed anymore, so when concatenating strings, it's actually create a new String instance to store the concatenated string values. For example, below is a simple string concatenation example. Str...

   JAVA,STRING,JAVA 8     2019-01-18 22:07:12

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