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  Is Java Set ordered or not?

“Is Java Set ordered or not? ” is the most popular question asked when you interview for a Java Developer position. Many fail to answer it, and I have to admit I was one of the many. I have known the answer is “Yes and No” for a long time. No. HashSet is not ordered. Yes.TreeSet is ordered. If the interviewer continues with some follow up questions, I’m not confident that I know the answer then. Why is TreeSet ordered? Are there any other ordered S...

   ORDER,SORTEDSET,HASHSET,JAVA     2021-02-11 06:55:00

  MySQL Index Merge Optimization Practices

In production environment databases, it is often seen that some SQL where conditions include: equal condition on a normal index + primary key range query + order by limit Although using a normal index would be more efficient, the system chooses to use index merge instead in some cases. This article explores such index merge situations. Index Merge Official Introduction   The Index Merge access method retrieves rows with multiple range scans and merges their results into one. Generall...

   INDEX MERGE,MYSQL,PRIMARY INDEX,SECONDARY INDEX     2024-09-10 04:52:26

  File upload in PHP

File is a special kind of form data, when being uploaded to the server through HTTP POST request, PHP will create a $_FILES global array, the relevant file information will be stored in this global array. We will illustrate file upload with some code snippets using PHP and look into the internal work mechanism. Lastly will talk about file upload security. File upload In order for users to upload files in client side, we have to provide a form on the user interface. Since the uploaded file is a s...

   File upload,PHP     2012-11-30 22:01:28

  Understand GoLang WaitGroup internals and how it works

Background Before getting into the main content, let me give a brief introduction to WaitGroup and its related background knowledge. Here, the focus is on the basic usage of WaitGroup and the fundamental knowledge of system semaphores. For those who are familiar with these, you can skip this section directly. WaitGroup WaitGroup is one of the most common concurrency control techniques in Golang, and its function can be roughly compared to the join() in concurrency control of other languages' mul...

   GOLANG,WAITGROUP,SOURCE CODE     2023-04-26 08:02:01

  Python PLC Honeypot Project

Program Design Propose : This project aims to develop a sophisticated honeypot system that emulates an OT (Operational Technology) SCADA network environment, bridging Level 1 OT field controller devices (PLCs) with Level 2 control programs, including Human-Machine Interfaces (HMIs). This honeypot will simulate various PLC models from major vendors, such as Schneider and Siemens, while supporting the primary communication protocols Modbus-TCP and Siemens-S7Comm. The system will integrate essenti...

       2024-11-25 03:56:49

  The First Bite on etcd Code

Etcd, one of the crucial components of Kubernetes. If APIServer is the heart, then etcd is the blood vessel that sends the end state of Kubernetes resources to various “organs”, providing high-speed, stable storage, and supporting APIServer’s high load performance. What if the etcd is not working properly? Just the condition as someone has a vascular disease. The deeper you know about them, the better diagnose you can make when issues occur. from unspl...

   SOURCE CODE,ETCD     2022-02-12 01:03:14

  What is pjax and why we should use it?

What is pjax? Now many websites such as Facebook, Twitter support one browsing style which is when you click one link on their sites, the page will not be redirected, instead only the page contents are updated and URL on address bar is changed. This kind of user experience is much better compared to load the whole page with a blink. There is one important component in the above browsing experience, these websites' AJAX refresh support browser history, when refreshing the page, the address on the...

   pjax,AJAX,history     2013-04-23 12:22:37

  OT Railway System Development: How to Use PLC to Implement Land Based Railway Track Fixed Block Sign

Figure-00: Railway fixed block signaling system over view diagram, version v1.3 (2024) Project Design Purpose: This project aims to use Programmable Logic Controllers (PLC) with train detection sensors and train control signals to develop an automated OT system for railway track fixed block signaling control. The system will include a digital equivalent simulation to explain the logic of the track fixed block Automatic Train Control (ATC) mechanism for demonstration and training purposes. In th...

       2024-07-27 04:08:41

  Be Aware of these 10 mistakes while designing Your Mobile App!

So you have finally decided to enter the world of technology and you are going to design an application for your business. The time has become when you have to give all the nitty-gitty grins a look and design your own mobile app for promoting your business online. Well when you have finally decided to design your mobile application, here are some mistakes that you are not allowed to make. Have a look:   Do Not Start Designing Your App Without Wireframes Normal 0 false ...

       2014-12-11 02:12:02

  Go 1.16 is released

Note: The post is authorized by original author to republish on our site. Original author is Stefanie Lai who is currently a Spotify engineer and lives in Stockholm, original post is published here. Last week, Go1.16 was released, bringing relatively more changes than version 1.15, which was influenced by the epidemic. The update is in many aspects, including compilation, deployment, standard library, etc. In the official Go document, all changes are classified based on Too...

   GOLANG,GO1.16,NEW FEATURES     2021-02-26 21:08:42

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