SEARCH KEYWORD -- STRICT COMPARISON


  What will the value of Integer.valueOf(127) == Integer.valueOf(127) be in Java?

Do you really understand how Java does the integer comparison? OK, ignore the statements in the post title. What we are interested in is another set of comparison statements. Let's first see below code snippet. public class IntegerComparison { public static void main(String[] args) { Integer a = 127, b = 127; Integer c = 128, d = 128; System.out.println(a == b); System.out.println(c == d); } } What do you think the output will be? Are they both displaying true? You will find out t...

   JAVA,==,EQUALSTO     2018-01-13 22:18:15

  SameSite attribute in cookie

Starting from Chrome 51, a new attribute SameSite has been introduced for browser cookie. This attribute is to prevent CSRF attack. Cookie is normally used to store data exchanged between client and server. It frequently stores user login information. If a malicious website can forge a HTTP request with the valid third party website cookie, it may be called a CSRF attack. For example, if a user logins to a bank website your-bank.com, the bank server responds a cookie: Set-Cookie:id=a3fWa; L...

   JAVASCRIPT,COOKIE,SAMESITE,CHROME,CSRF     2019-09-14 04:57:51

  Use downcase! with caution in Ruby

Ruby provides ! to change state of some object in place. Hence if you see some functions have ! appended, it means the state of the caller of the function is expected to be changed. This is a very interesting Ruby feature. But sometimes one should be cautious when using this kind of functions because you would get unexpected behavior if using improperly. Let's take an example of String#downcase!. According to the documentation. Downcases the contents of str, returning nil if...

   RUBY,EXCLAMATION MARK,DOWNCASE     2017-02-10 06:34:44

  Arrays.equals() vs MessageDigest.isEqual()

Both Arrays.equals() and MessageDigest.isEqual() are used to compare the equality of two arrays. They can be interchangeably in many cases. However, they do have some differences which lead to different use cases in real applications. One difference is that the arrays passed to MessageDigest.isEqual() cannot be null while it's ok for Arrays.equals(). The one major difference between these two methods is that Arrays.equals() is not time-constant while MessageDigest.isEqual() is time-constant. Thi...

   Arrays.equal(),MessageDigest.isEqual(),Java,Security     2015-05-14 22:03:29

  Top 10 essential Java classes

When we write Java programs, we will frequently use some classes such as java.lang.String. There are some essential Java classes which we may use frequently, there is no strict rules for the selection of essential Java classes, in fact there are no rules followed. It depends on what projects you are doing or what you have done,, so every one may have his own choices about the top essential Java classes in his mind. Here we list the top 10 essential Java classes you may agree with.1. java.lang.St...

   Java,class,essential class,top 10     2012-06-04 09:44:19

  Integer overflow

You may be familiar with integer overflow, but what you may not be familiar with is how gcc handles signed integer overflow. First let's look at the standard, for unsigned integer, the standard says : A computation involving unsigned operands can never overflow, because a result that cannot be represented by the resulting unsigned integer type is reduced modulo the number that is one greater than the largest value that can be represented by the resulting type. In other words, unsigned integer ov...

   Integer overflow,gcc,Linux     2012-10-20 13:33:10

  Have Apple considered to develop iPad for aerospace use?

Today, I read article about China's Shenzhou 9 Spacecraft which is expected to be launched in middle of June. In this article, it mentions that the Chinese astronauts may bring some mobile devices with them in order for them to relax in such a long journey to outer space. The most probable devices they may bring are some tablets because laptops are too heavy to be placed in spacecraft which has limit space and weight capacity., while smartphones are too small and not so convenient for astronauts...

   Apple,iPad,Aerospace,Shenzhou 9     2012-06-14 05:41:20

  this in JavaScript in detail

this in JavaScript is always confusing, it is one of the most frequently seen traps in JavaScript. this is not a good design in JavaScript(You can refer some other design flaws of JavaScript here), since it's lazy binding feature, it can be a global object, the current object or.... Some people even avoid using this in JavaScript. Actually if you master how this works, then you will know how to stay away from these traps. Let's take a look at what this points to in below situations. 1. In global...

   JavaScript,this,bind     2013-05-09 18:35:12

  Can two new objects point to the same memory address in GoLang?

Do you have any idea what the output will be for below GoLang snippet? package main import ( "fmt" ) type obj struct{} func main() { a := &obj{} fmt.Printf("%p\n", a) c := &obj{} fmt.Printf("%p\n", c) fmt.Println(a == c) } Many people would think that a and c are two different object instances which have different memory addresses. Hence a == c will be false. But if you try to run the above program, you would see below output 0x5781c8 0x5781c8 true To get to know the reason wh...

   GO,GOLANG,VARIABLE ESCAPE,ZEROBASE     2019-04-06 01:19:52

  A mini guide to HTTP referer

In HTTP header, there is a field named Referer which is to provide the referrer of the current accessed page. In this post, we will introduce the usage of HTTP referer field. On the web, when a user visits a webpage, s/he must be from some place. This place is usually referred a s referer. This information is very important to some website operators and server owners as they want to know where they get the traffic from and this helps them provide better service for potential targeted users. In t...

   HTML,HTTP REFERER,REFERRERPOLICY     2019-06-29 02:23:25

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