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  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


  Is Scala Only for Computer Scientists?


I have experience struggling through these kinds of things andI know enough about the subject that I can understand why they did it that way. But my concern is that this should be an example that a beginner could understand, and they can't. There's too much depth exposed. Here's the example, which is written as a script: import scala.io.Source._ case class Registrant(line: String) { val data = line.split(",") val first = data(0) val last = data(1) val email = data(2) val payment = da...

   Scala,Application field,Computer science     2012-02-17 07:46:40


  Cleansing data with Pig and storing JSON format to HBase with Pig UDF


Introduction This post will explain you the way to clean data and store JSON format to HBase. Hadoop architect experts also explain Apache Pig and its advantages in Hadoop in this post. Read more and find out how they do it. This post contains steps to do some basic clean the duplication data and convert the data to JSON format to store to HBase. Actually, we have some built-in lib to parse JSON in Pig but it is important to manipulate the JSON data in Java code before store to HBase. Apache Pig...

   JSON,HADOOP ARCHITECT,APACHE HBASE,PIG UDF     2016-06-10 01:13:41


  Java is not the new COBOL


If you Google “Java is the new COBOL” you’ll find a glut of articles proliferating this mantra. I don’t know its origins, however I’m inclined to think it’s mostly repeated (and believed) by the Ruby community. Ruby, from a developer’s perspective is a low-friction language. A developer can just sit down at a text editor and start banging out code without really thinking about such superflous things as types. Java on the other hand, well, you have to think a lot about types. J...

   Java,Ruby,Type,COBOL,Comparison     2011-11-10 10:40:56


  A Month With Scala


Although I’ve played around with Scala for the few months, these efforts largely involved simple scripts and casual reading. It wasn’t until last month that the opportunity to use Scala in a large scale project finally arose and I dove right in. The project was a typical REST based web service built on top of Amazon’s Elastic Beanstalk, SimpleDB, S3 and Redis*. First off let’s talk about why I chose Scala in the first place. After spending a good deal of my last year entrenched in...

   Scala,Functional,OOP,Java,Iteration     2011-12-10 06:03:23


  Java Sequential IO Performance


Many applications record a series of events to file-based storage for later use.  This can be anything from logging and auditing, through to keeping a transaction redo log in an event sourced design or its close relative CQRS.  Java has a number of means by which a file can be sequentially written to, or read back again.  This article explores some of these mechanisms to understand their performance characteristics.  For the scope of this article I will be using pre-a...

   Java,IO,Sequential,Blocking     2012-02-23 07:09:10


  A boolean value interview question


Someone asked a question on StackOverflow, he was asked an interview question. The question is : Given 3 boolean variables a, b, c, return true if at least 2 out of the 3 are true. He gave the solution as follows :boolean atLeastTwo(boolean a, boolean b, boolean c) {    if ((a && b) || (b && c) || (a && c)) {        return true;    } else {        ret...

   bool,return,expression,conditional     2012-04-30 08:49:32


  Haskell’s effect on my C++: exploit the type system


Like most programmers, I was attracted to Scheme by the promise that it would make me a better programmer. I came to appreciate the functional style, but swapped to Haskell, a more developed language with a rapidly developing standard library. Unfortunately, for me, Haskell can’t yet replace C++ on a day to day basis, so I reluctantly spend my days tapping away at C++. So, were the promises true? has functional programming made me a better programmer? Better is a tough question, I ha...

   Haskell,C++,Type system,Comparison     2012-02-06 07:44:35


  Understanding lvalues and rvalues in C and C++


The terms lvalue and rvalue are not something one runs into often in C/C++ programming, but when one does, it’s usually not immediately clear what they mean. The most common place to run into these terms are in compiler error & warning messages. For example, compiling the following with gcc: int foo() {return 2;} int main() { foo() = 2; return 0; } You get: test.c: In function 'main': test.c:8:5: error: lvalue required as left operand of assignment True, this code is so...

   lvalue,rvalue,C++,locator value,elaboration     2011-12-15 07:51:38


  8 very useful and free web security testing tools


With more pervasive of web applications, web security threats are becoming increasingly prominent. Hackers gain web server control by exploiting web server vulnerabilities and SQL injection vulnerabilities, then they may tamper with web content, or steal important internal data, the more serious is to inject malicious code into web pages to affect visitors of websites. Attention is gradually warming up to Web Application Security. Here we recommend eight very useful and free web security testing...

   Website, security,Web security,Attack     2012-07-22 10:59:09