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  Different ways to print "Hello world" in Java

This post is not about best practice to print "Hello world" in Java, it is about exploring different capabilities offered by Java. Also there are articles about printing "Hello world" in different programming languages, but this post is not about that. Standard literal The most commonly used way is to use System.out to print"Hello world". System.out.println("Hello world"); Enumeration An enumeration can define a set of values belonging to one category. For example, an enumeration for all months ...

   JAVA,FEATURE     2016-05-21 21:49:48

  New features in Java 9

Java 9 is planned to be released in March 2017. It will be 3 years since Java 8 was released. Are you still excited about the new features introduced in Java 8 such as Lambda, new Date APIs etc? Now Java 9 is to be released and there are also quite a few fantastic new features to be introduced. Below is a list of major new features in Java 9. Modular system. Java 9 will introduce a brand new modular system to organize Java codes. The modular system will divide different packages into diffe...

   JAVA,NEW FEATURE,JAVA 9     2016-04-05 09:56:01

  Will nil == nil be true in GoLang

There is some interview question may ask whether nil == nil be true in GoLang. Wil it be true. false or compilation error? To know the answer, some knowledge about nil in GoLang needs to be explained first. nil definition According to Go's official documentation, the definition of nil is // nil is a predeclared identifier representing the zero value for a // pointer, channel, func, interface, map, or slice type. var nil Type // Type must be a pointer, channel, func, interface, map, or slice type...

   GOLANG,NIL,NIL EXPLANATION     2021-08-08 02:54:15

  Install and setup Kafka on Windows

Kafka has become a very popular distributed message delivery service which decouples different services while making message delivery between service easy, fast and reliable. In this post, we will walk through how to install and set up Kafka on Windows. Pre-requisite Java Apache ZooKeeper Installation Go to Kafka's download link and download the latest stable release, we downloaded 2.2.0 as of this writing. After downloading, copy the installation file to some folder and unzip it.  Sinc...

   KAFKA,STREAM,USER GUIDE     2019-06-01 02:12:07

  Is Facebook becoming Tencent like?

Recently there is news that Facebook is developing a Reader application which is to compete with Flipboard and Pulse. This reminds me a few movements of Facebook in the past few months. First they built a copy of Snapchat named Poke which failed badly at last. Then they launched a new feature on Instagram named Video on Instagram which allows users to shoot and share short videos up to 15 seconds. This feature is to compete with Vine from Twitter. It seems Instagram wins over Vine on this. You c...

   Facebook,Tencent,Copy     2013-06-24 01:17:27

  One Way to Quickly Locate SQL with High CPU Usage in MySQL

When the CPU usage of a MySQL database rises abnormally, it's necessary to quickly identify the problematic SQL statements. In this post, we try to provide one way to achieve this.  Below are the actual steps. 1. Use the top command to find the threads with the highest CPU usage in the MySQL process. # Find the MySQL process ID ps -ef | grep mysql # Use the process ID to find the thread IDs with the highest CPU usage: top -H -p In top, press P to sort by CPU usage. Note the thread ID, fo...

   MYSQL,DEBUG,HIGH CPU,SLOW QUERY     2024-08-01 21:25:48

  Java AbstractMethodError explained and demonstrated

According to Oracle Java API documentation, AbstractMethodError is a kind of runtime error where the application is having some incompatible changes which leads to a missing implementation of an abstract method. Below is the official description. Thrown when an application tries to call an abstract method. Normally, this error is caught by the compiler; this error can only occur at run time if the definition of some class has incompatibly changed since the currently executing method was last co...

   JAVA,ABSTRACTMETHODERROR     2016-07-22 22:03:20

  4 Things Every Great Online Teacher Knows

Virtual classrooms have become the new norm for education during the pandemic. Teachers from every school have to adjust to this new reality to ensure students keep learning even in the absence of a physical classroom setup.  Thankfully, there are various digital solutions to help teachers conduct online classes without much hassle. One such tool that has revolutionized the online learning market is a Learning Management System (LMS). For schools, the in-house learning management department...

   EDUCATION,ELEARNING,ILEARNING     2021-02-12 03:23:43

  9 reasons to use Zsh

Like majority *nix users, I have been using bash for many years. Sometimes I feel uncomfortable with bash. I tried use some other shells as well such as ksh, tcsh and zsh which I am going to talk about. A few days ago, I found an open source project ranking in the 6th named oh-my-zsh on Github, I downloaded it and had a try with it. It's amazing. We should use zsh to replace bash now. Why do we need to use zsh? Here is a 4 minutes YouTube video which shows many reasons why we should switch from ...

   zsh, advantage, command     2012-09-28 12:46:39

  Why is single threaded Redis so fast

Redis is a high-performance, in-memory key-value database. According to official test reports, it can support around 100,000 QPS (queries per second) on a single machine. However, Redis uses a single-threaded architecture in its design. Why does Redis still have such high performance with a single-threaded design? Wouldn't it be better to use multiple threads for concurrent request processing? In this article, let's explore why Redis has a single-threaded architecture and still maintains its spe...

   REDIS,SINGLE-THREADED,MULTI-THREADING     2023-02-28 05:16:22

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