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  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

  How to handle ES6 modules in NodeJS

In modern JavaScript, there are two types of modules: ES6 module and CommonJS module used by NodeJS. These two types of module are not compatible. Many people would wonder how to load ES6 modules in their NodeJS project. This post will show how this can be done. Difference The syntax of the module being loaded is different. CommonJS modules are loaded with require() and exported with module.exports. ES6 modules are loaded and exported using import and export respectively. Merchanismwise require(...

   NODEJS,COMMONJS,ES6     2020-08-28 22:01:33

  Why exception would be thrown when deleting element while looping through HashMap in Java

HashMap and other Collection types are frequently used in Java application programming. This post will explain why exception would be thrown when deleting element with Map.remove() while looping through a Map using Iterator. This issue would also occur to other Collection types such as Set, List. Below is a sample code snippet demonstrating the exception thrown. Map<String,String> map = Collections.synchronizedMap(new TreeMap<String,String>()); map.put("key1","value1"); map.put("ke...

   JAVA,HASHMAP,CONCURRENTMODIFICATIONEXCEPTION     2018-06-30 12:49:09

  HTML above flash (transparency + z-index)

We have faced this problem many of the times. When we want to display some message on top of all layers on a page or use some feature like jQuery light boxes. Normally the flash file continues to shine through the page. No matter what you do with layering the dom elements using z-index.See the layering flash content problem definition here.Before this, people used to dodge this issue with some fixes like hiding the flash area completely and then showing a static image of...

   HTML,Flash,Above,z-index,wmode,transpare     2011-05-01 15:46:34

  Language Complexity?

Some languages are complex, others are simple … right?  C++ versus just about anything else is a good example here.  But, it begs the question: what makes a language complex? So, I’ve just been reading Bruce Eckel’s Artima article on Scala.  It’s actually a nice article, and I enjoyed it.  But, one thing bugged me — and, it’s nicely summarised in this quote: But you can see from the code above that learning Scala should be a lot eas...

   Programming language,complexity     2011-06-15 02:16:05

  Check file readability in Java

File operation is quite platform dependent. Although Java is a cross platform programming language, the file operation in Java is also platform dependent. The obvious evidence is the file permission check. In Java, we can call canRead(), canWrite() and canExecutable() to check whether the program can read, write or execute the file specified. However, on Windows, when we call canRead() on a File object, we may get unexpected result. Actually, on Windows, when we call canRead() on a File object, ...

   Java,Files,Readable,Check     2013-12-05 06:10:15

  What else is new in C# 5?

The big new feature in C# 5 is asynchronous programming support, which I wrote about last week. However, the C# folks have also slipped in a couple of smaller features and I thought I’d round things out by mentioning those. Method caller information There’s a complete style guide to be written on Writing Enterprisey Code, but one of my favourite “enterprisey” tells, after the use of Visual Basic, is obsessively logging every function you pass through: Function Ad...

   C# 5,New feature,Analysis     2012-03-20 07:45:11

  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

  Deep Understanding of ReentrantLock: Unlocking the Mysteries of Java Concurrent Programming

ReentrantLock introduction ReentrantLock is a class in the Java concurrent package, java.util.concurrent.locks, and is an implementation of the Lock interface. As its name suggests, it is a reentrant mutual exclusion lock. A mutual exclusion lock is a synchronization tool used to protect shared resources, ensuring that only one thread can access the resource at a given time. Reentrant means that a thread can acquire the same lock multiple times without causing a deadlock. This lock provides some...

   JAVA,REENTRANTLOCK,CONCURRENCY,MULTITHREADING     2023-05-22 08:01:13

  Canonicalize XML in Java

XML canonicalization is often used when there is need to create digital signature to be sent to peers for verification. Since digital signature is created based on XML data, the XML data has to be canonicalized before its signature value can be calculated. Even an extra space may affect the signature value calculated, hence it must follow some rules to canonicalize the XML data so that it has a standard format. This is why W3C created specification Canonical XML Version 1.1. This specificat...

   JAVA,XML,JAVA SECURITY     2016-01-20 01:39:45

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