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  Java Concurrency Basics: CountDownLatch and CyclicBarrier

CountDownLatch CountDownLatch can be used in synchronizing behavior among threads, it makes one or more threads wait for some actions in other threads to be completed. It has a property count which defines how many countDown() need to be called before other threads which called await() to be waked up.  When a thread calls CountDownLatch.await(), the thread will be blocked until the value of count becomes 0. The initial value of count can be specified when creating the CountDownLatch instanc...

   JAVA,JAVA CONCURRENCY,COUNTDOWNLATCH,CYCLICBARRIER     2018-03-25 07:02:40

  Using MemoryMappedBuffer to handle large file in Java

When handling large files, it will largely affect the process speed while using traditional FileInputStream, FileOutputStream or RandomAccessFile since they trigger lots of read and write operations. In Java NIO, a new way of handling large file is introduced which is to use MmeoryMappedBuffer to create memory mapped file. Memory-mapped I/O uses the filesystem to establish a virtual memory mapping from user space directly to the applicable filesystem pages. With a memory-mapped file, you can pre...

   JAVA,IO,NIO     2015-11-13 01:58:08

  Set Theory in C++11

Have you ever felt the need to perform set theoretic operations on types? Not really? Me neither, but I thought it’s a fun thing to try out. So, if you ever feel the need of using type sets, C++11 makes it quite easy to do so. Especially variadic templates allow for a much more condensed syntax compared to type list constructs formerly used. (Disclaimer: This is rather a proof of concept, but maybe somebody comes up with a useful scenario.) Let’s start by d...

   C++,set theory,Math     2012-03-11 13:15:55

  Apple CEO criticizes Windows 8 on D10

In the D10 Digital Conference held by The Wall Street Journal, Apple’s CEO Tim Cook expressed his sharp criticism about Windows 8 to be launched by Microsoft. According to Cook, the idea of this OS attempting to perfectly apply to both tablet and PC is far from realistic.On D10, Tim Cook said : "[With Windows 8, Microsoft] is pulling all of the leg weight of the PC market. You wind up with something that's very similar to what tablets were 10 years ago. The more you look at combining th...

   Apple CEO,Tim Cook,Windows 8,D10     2012-05-31 05:31:32

  Display GIF animation while submitting the web form

Internet appears everywhere in our life. Form as a data gathering component is the must have component in a web app. When the page is submitting data to the server, if it takes a relative long time for the backend server to process the data, then the client users will feel lost while waiting for this if he cannot get any indication about what's happening. They may even reclick the button which will cause the data resubmission. This affects the user experience and also the system performance and ...

   HTML,Spin,Submit,Form     2013-05-17 11:47:07

  3 meanings of Stack

We may frequently see stack when we read programming books. But many times we may be confused about the different meanings of it. This term actually has three common meanings. Here we explain the three different meanings of Stack in programming. 1. Data structure The first meaning of Stack defines a method for storing data. Its feature is LIFO9Last In First Out). In this data structure, data are accumulated level by level. The data last put in is added at the top of the stack. When using the dat...

   Stack,Memory,Data structure     2014-02-24 04:56:46

  bash network interface

Some of us may have seen /dev/tcp/<host>/<port> before, is this a special file system implemented in some BSD kernel? Because there is no /dev/tcp in Linux. Actually, this one is implemented in bash. We no need to rely on wget,nc to do network connection. It's very easy to use this interface: bash-4.2$ cat </dev/tcp/time.nist.gov/13 56188 12-09-18 15:34:26 50 0 0 733.5 UTC(NIST) * bash-4.2$ exec 3<>/dev/tcp/www.w3.org/80 bash-4.2$ echo -e "GET / HTTP/1.0\n\n" >&3 b...

   Bash,Network interface,/dev/tcp     2013-07-20 00:57:52

  ScrollerJS vs Odometer

Both ScrollerJS and Odometer are two JavaScript libraries to transition one number to another number with animation. They provide user a fancy animation about scrolling numbers. These libraries can be used in many scenarios such as user statistic counter, timer or odometer. This post is going to have a comparison on these two open source libraries. Below is a table which lists the features the two libraries have: Feature ScrollerJS Odometer Language JavaScript and CSS JavaScript and CSS S...

   JavaScript, Odometer, ScrollerJS, Open source, CSS Transition     2015-05-13 02:10:55

  Generate certificate in Java -- Certificate chain

In previous post, we have introduced the use of Certificate and how to generate self signed certificate using Java. In this post, we will show you how to generate a certificate chain. Sometimes we may only have a certificate request or we don't have a trusted certificate which can be used for business. Now we need to have a trusted CA to sign our certificate so that it can be used on SSL communications. To generate a certificate chain, we may first have our own certificate(A), then we may use ot...

   Java,Certificate chain,Creation, Pure Java     2014-07-30 08:24:52

  Generate certificate in Java -- Store certificate in KeyStore

In previous post, we have explained how to create a certificate chain in Java. After generating the chain, we need to store it somewhere so that it can be used later when we are doing the actual SSL communication, either in a key store or trust store. This post will show you how to store the private key and its associated certificate chain in a keystore file. There are different types of keystore in Java, in this post, we will choose the JKS to demonstrate how to store the certificate chain. Whe...

   Java,Certificate chain,Keystore     2014-08-20 03:56:39

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