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  Loading images progressively using Gaussian blur

The popular online publishing platform Medium has adopted an impressive image loading mechanism -- pure color - blur image loading - real image loading. Since images on Medium usually have high definition, it takes much time to load an image and hence brings a bad user experience if rendering the image after it's completely downloaded. The solution Medium comes out is to preload an small image when the real image is being loaded.  On Medium, the HTML code will have below pattern ...

   JAVASCRIPT,ALGORITHM,GAUSSIAN BLUR,MEDIUM,BLUR IMAGE     2016-09-25 03:33:00

  Undefined property or variable in JavaScript

JavaScript is a weak type language, and also you can use a variable or property where it's undefined. If we don't have correct ways to check whether a property or variable is defined, we may get unexpected results when we try to access the,. How can we check whether a property or variable is undefined? This is actually a somewhat tricky question. Let's start off with some facts about undefined and then see what kind of function is consistent with the ones we care about. JavaScript attaches type...

   Property,Undefined,Array,JavaScript     2014-07-24 06:56:07

  CSS3 animation vs CSS3 transition

Both CSS3 animation and CSS3 transition can be used to transition an element in a webpage. They can be used to transition some CSS properties within a given period of time. They have many similarities. They do have a few differences as well. So an user needs to understand the differences between them in order to better use them in different scenarios. First, let's see an example on how to change the width of a div from 100px to 200px within 2 seconds when hovering on it. With CSS3 animation , th...

   CSS3 animation,CSS3 transition, Difference     2015-06-15 08:46:39

  Guide for installing Ubuntu in VirtualBox on Windows

Have you ever tried to have two OSs installed on your PC? Do you want to try out the new Ubuntu system? If you do want to use Ubuntu when at the same time you are using Windows, you may want to install your Ubuntu in an VirtualBox. In this post, we will show you how to install Ubuntu in VirtualBox on Windows. Pre-requisites VirtualBox -- You can download it from Oracle. Ubuntu -- You can download it from here. Please note it should be an ISO file The Ubuntu used in this post is Ubuntu 12.04 LT...

   Ubuntu,Windows,VirtualBox     2014-01-15 03:21:05

  Generate certificate from cert file in Java

A certificate is often used to prove the identity of a server. The certificate will contain information such as the subject and issuer of the certificate. It will also contain the validation date of the certificate. A certificate is often exported to an external cert file which is transferred over the internet. We will often see its use in SSL communication which provides secure communication between two entities. In this post, we will show how to read the data from an external certificate file ...

   PKCS12,CertificateFactory,Example,Java,X509     2015-06-08 06:47:05

  Generate first N prime numbers

Recently I am taking an online course named "Startup Engineering" on coursera. There is one assignment which is to use NodeJS to write a program to generate the first 100 prime numbers. This may be very easy for many people. Here I just want to share with you the code to generate not only the first 100 prime numbers. but also any number of prime numbers. Below is the code snippet: //Helper class to generate prime numbers var PrimeProcessor=(function(){ var primeArray=[]; functio...

   Algorithm,Prime number,NodeJS,coursera,JavaScript     2013-06-29 22:08:22

  Memory related exception analysis in Java

Java Virtual Machine Specification divides the memory of JVM into several areas : Heap, Stack, The Program Counter register and Method area etc. In HotSpot JVM, heap is composed of Young, Tenured and Perm. There are different OutOfMemory error can happen in different memory area. Next is an overview of some of these OOM errors. StackOverflowError The JVM will allow only a specified number of stacks created nested. An JVM option -Xss can be set to determine the maximum stack size. If the num...

   Java, Memory model, Memory exception, OOM     2015-01-19 06:54:27

  Optimization Tricks used by the Lockless Memory Allocator

With the releasing of the Lockless Memory Allocator under the GPL version 3.0 license, we can now discuss more of the optimization tricks used inside it. Many of these are things you wouldn't want to use in normal code. However, when speed is the ultimate goal, sometimes we need to break a few rules and use code that is a little sneaky.The SlabA slab is a well-known technique for allocating fixed size objects. For a given object size, a chunk of memory is divided up into smaller regions of that ...

   Optimization,Memory allocation     2011-11-16 08:02:16

  Use Java ThreadLocal with caution

According to Oracle documentation, ThreadLocal is a class provides thread-local variables. These variables differ from their normal counterparts in that each thread that accesses one (via its get or set method) has its own, independently initialized copy of the variable. ThreadLocal instances are typically private static fields in classes that wish to associate state with a thread. In short, ThreadLocal variables are variables belong to a thread, not a class or an instance of a class. One common...

   JAVA,MEMORY LEAK, THREADLOCAL     2015-11-03 07:31:57

  JShell -- The command line tool to run Java code in Java 9

Java 9 is currently a work-in-progress and is planned to be GAed in March 2017. Quite a few new features will be introduced in the new release. The coolest feature is project Jigsaw which is to modularize the Java packages so that a customized JDK can be built and shipped with only the necessary modules to fulfill their project requirement. Apart from this feature, another big new feature is project Kulla -- JShell. In simple, JShell is a command line tool which can be used to run...

   JAVA 9,JSHELL,KULLA     2016-04-01 21:46:48

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