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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

  About browser event

First look at following codes: var $ = KISSY.all; $(‘a’).on(‘click’,function(e){ doSomeThing();//This function seems very famous e.halt(); }); The above codes seem complete the work we want them. The browser will not redirect us to the link in href, but is there some issue with the codes above? Before explaining what's wrong with the above codes, we first need to understand some concepts. Browser default behavior When we click a link, the browser will redirect us to anoth...

   JavaScript event,Event bubbling,event capturing     2012-11-15 11:15:41

  Mock Solutions for GoLang Unit Test

In Go development, Unit Test is inevitable. And it is essential to use Mock when writing Unit Tests. Mock can help test isolate the business logic it depends on, enabling it to compile, link, and run independently. Mock needs Stub. Stub function replaces the real business logic function, returns the required result, and assists the test. I involved the related test code for Controllers while writing Kubernetes Operator recently, and there would be mocks for GRPC and HT...

   UNIT TEST,TESTIFY,GOSTUB,GOMOCK     2020-10-31 21:59:15

  One thought about JavaScript exception handle

Due to network, browser and cache issues, the JS executed in production may produce different results from the testing environments. Sometimes they may produce exceptions. Front-end developers may encounter this kind of exceptions frequently. But how to log and use them is seldomly considered by them. Actually, exception handling includes two steps : log and use. 1. Log Regarding to log error, this is relatively convenient, since in each browser, there is one interface called window.onerror. win...

   JaavScript,Log,Exception,Email     2013-03-18 12:50:21

  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

  4 deployment modes of Redis

As a high-performance in-memory database, Redis is widely used in current mainstream distributed architecture systems. To improve system fault tolerance, using multiple instances of Redis is also inevitable, but the complexity is much higher than that of a single instance. This article mainly introduces the four deployment modes of Redis and their advantages and disadvantages. Standalone Standalone mode is to install a Redis, start it, and business connects to it and that's all. The specific ...

   REDIS,STANDALONE,MASTER-SLAVE,SENTINEL,CLUSTER     2023-03-03 21:35:09

  2D Indoor CQB Robot Simulation

Program Design Purpose: The integration of robots in Close Quarters Battle (CQB) represents a significant advancement in modern military and law enforcement tactics. These robots, designed to navigate tight spaces, gather real-time intelligence, and engage threats, are invaluable assets in high-stakes scenarios. Our goal is to develop a 2D tactical board simulation system, similar to a computer game, that can load building floor blueprints, display CQB squad (robot) positions, enemy locations, ...

       2024-08-11 08:40:31

  IoT System Cyber Attack Case Study 02: Python Deserialization Attack and Library Hijacking Attack

Project Design Purpose: The objective of this cyber attack case study is to develop a workshop that demonstrates how a red team attacker can permanently compromise a people detection radar IoT device. The attack path is achieved through a series of attacks, including traffic eavesdropping, data deserialization attacks, web shell attacks, remote command/code execution, and Python library hijacking attacks. This case study is intended for IoT and data security professional training, aiming to ill...

       2024-07-14 01:40:09

  Power Grid Simulation System 02 : FDI Power Outage Attack Case Study

We are excited to share that the Power Grid Simulation System we developed was used as part of one red team's targeted critical infrastructure system the international cyber exercise Crossed Swords 2024 which conducted in December 2024. In this article, we will introduce one power outage attack case study which use the Power Grid Simulation System as the demo platform for OT cyber security workshop. Project Design Purpose: This case study demonstrates using the Power Grid Simulation System as a...

       2025-01-11 07:35:45

  About .NET memory leak--GC,Delegate and weak reference

Memory leak is always a headache for many programmers, the situation is much better now in some languages which have GC mechanism, but still we may face some memory leak issues when we write programs. 1. What is memory leak? Memory leak is not that the memory chip is broken. In short, it's about that the memory requested is not released at the expected time as an expect way. So what is the expected time? This is very important for you to understand memory leak. If the time an object taking the m...

   .NET,GC,Reference counting,Mark and sweep,Weak reference     2013-05-25 12:59:09

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