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SEARCH KEYWORD -- Reference counting

  String intern in Java

In Java, == is used to compare whether two objects have the same memory location, equals() is usually used to compare whether two objects have the same time and the same state.  When comparing two strings, normally we just want to know whether they have same content, so we can choose equals(). But since String comparison is so frequently needed, Java has worked on the String class to make == workable when comparing two String literals. The String class maintains a pool of emp...

   JAVA,STRING     2016-04-10 03:35:25

  CSS position explained

CSS has two very important properties on determining the position of an element in webpage: display and position. display is used to determine how elements are grouped and displayed on the page. While position is used to determine the exact position of an element on a page. And this post would explain position property in detail. position is used to determine the exact position of an element on a page. It has five possible values. static relative absolute fixed sticky sticky is supported start...

   CSS,STICKY,CSS3     2019-11-22 19:57:52

  A Perl Regular Expression That Matches Prime Numbers

perl -lne '(1x$_) =~ /^1?$|^(11+?)\1+$/ || print "$_ is prime"' Can you figure out how it works? I give an explanation below, but try to figure it out yourself. Here is what happens when you run it: $ perl -lne '(1x$_) =~ /^1?$|^(11+?)\1+$/ || print "$_ is prime"' 1 2 2 is prime 3 3 is prime 4 5 5 is prime 6 7 7 is prime 8 9 10 11 11 is prime Here is how it works. First, the number is converted in its unary representation by (1x$_). For example, the number 5 gets converted into 1x5, which is ...

   Perl,Regex,Regular expression,Prime number,One line     2011-12-26 08:42:00

  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

  Android create button tutorial

This tutorial assumes that you already have an activity and are using an XML layout. Open the layout XML and add the button element.  Assign an ID with the “@+id” operator.  The + tells Android to generate an ID for this element so that you can reference it in your Java files. This is an example. Your layout and text elements will probably be very different. In this example case, the ID of the button is “close”. <Button android:id="@+id/close" android:lay...

   Android,Simulator,Button,XML,Tutorial     2014-11-07 08:30:10

  Standardizing Python WSGI deployment

Over the past year I have been testing all of the new python platform as a service companies that have popped up, and I have posted my notes on my blog so that everyone can learn from my experiences. ep.io, apphosted.com, gondor.io, dotcloud.com, DjangoZoom.com, Heroku, Django hosting roundup, All and all, the platforms were very similar, they allowed you to easily host your python/django project without having to worry about managing a server or other typical system administr...

   Python,Standard,WAR,Java     2011-12-31 15:39:44

  JavaScript tutorial - Creating time delays

There are two ways of creating time delays with JavaScript. The first is more simple and will simply wait for a specified amount of time before executing a function. The second does the same but will repeatedly execute the function. Note, many browsers have a minimum delay length of between 25 and 75 ms, with some of the fastest browsers having a minimum delay of about 3 ms. If a shorter delay is specified, the actual delay will be the minimum delay length. Even with higher numbers, the delay i...

   JavaScript,Time delay,setTimeout,setInterval     2012-04-13 07:17:46

  JavaScript tips both novice and veteran developers can benefit from

In this post, we will share some less known but powerful JavaScript tips which can benefit both novice and veteran JavaScript developers. 1. Truncate array with array length We all know that object are passed by reference in JavaScript, but we may be bitten by this rule. Please check below example: var arr1 = arr2 = [1, 2, 3]; //Change arr1 arr1 = []; // arr2 will still be [1,2,3] arr1 and arr2 point to the same array [1,2,3] initially, later when arr1 repoints to [], the reference to arr2 is n...

   JavaScript,Array,push     2013-08-21 04:09:10

  First steps with Scala, say goodbye to bash scripts…

Those who know me are aware that I’ve been following play framework, and actively taking part of it’s community, for a couple of years. Playframework 2.0 is right around the corner, and it’s core is programmed in Scala, so it’s a wonderful opportunity to give this object-oriented / functional hybrid beast a try… Like many others, I will pick a very simple script to give my first steps… Finding an excuse to give Scala a try With a couple of friends we are ...

   Scala,Functional programming,Bash script,Replacement     2012-01-12 06:45:16

  Deep clone of JavaScript object

In JavaScript world, it's frequently seen object clone. Normally when creating a clone of an object, it's only the reference being cloned but not all contents. In some scenarioes, it's desired to clone all the content instead of just the reference such that any change made to the cloned object will not change the original object. Differences between shallow clone and deep clone can be as simple as: Shallow clone : Only the object reference is cloned but not the content Deep clone : Clone all co...

   JAAVSCRIPT,DEEP CLONE,DEEP COPY,SHALLOW CLONE,SHALLOW COPY     2016-10-31 00:27:24

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