SEARCH KEYWORD -- System programming


  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

  New Features to Look Out for in Xcode 9

When we say Xcode, we mean a designing toolset which is completely packed with features. Using this Xcode, developers can create applications for platforms such as the Apple TV, the iPad, Apple Watch, and the iPhones and even for the Macintosh. The development system for Xcode has a mixture of features. These are called the instrument analysis tool, simulators, and the ever important OS frameworks which are present in the package in a variety of form of tvOS SDKs, iOS SDKs, watchOS SDKs, and the...

   XCODE,IPHONE,XCODE9     2017-09-26 06:31:30

  Why can System.out.println be used to exit while loop

Let's first take a look at one simple Java thread code snippet which is supposed to exit the while loop after the first loop run. public class StopThread { private static boolean stopRequested; public static void main(String[] args) throws InterruptedException { Thread backgroundThread = new Thread(new Runnable() { @Override public void run() { int i = 0; while (!stopRequested) { i++; } } }); backgroundThread.start(); TimeUnit.SECONDS.sleep(1); stopRequested = true; } } But the tr...

   JAVA,THREAD,VOLATILE     2018-12-21 19:25:54

  How do Silicon Valley companies recruit

There are a lot of friends asking me about the basic flow of how Silicon Valley companies recruit engineers. As a candidate, I tried Facebook, Google, Yahoo, Oracle, and I received offer from all these companies. As an interviewer, I have interviewed no less than 300 people and I know about the process of recruitment. I write this article with the hope of inspiring people who want to go to Silicon Valley or who are preparing for interviews or who are in the design of the recruiting process...

   Facebook,Interview,Experience,Silicon Valley     2012-05-15 06:36:52

  The tips of learning Linux kernel

  As the Linux kernel has become one of the most gigantic and complex software project in the world, its complication scare many novices away. In this post, I will give some personal experience on how to learn Linux kernel, and hope these tips can offer some help to newcomers. (1) Download vanilla kernel and install it. Yes, I suggest you can find a physical machine, or if you really don’t have one at hand, virtual machine is also OK. Download the newest vanilla k...

       2017-07-28 22:53:11

  Get hostname from a URL using JavaScript

Sometimes we may have strings which contain some UR;s and we may want to retrieve the hostname from the URLs for some statistic use. For example, we may have a URL : http://www.example.com/aboutus.html. We may want to retrieve the www.example.com from the URL. How? Use regular expression. Here I give an example using JavaScript. If you want to check whether a string is a URL or not. Refer to Detect URLs in a Block of Text. In JavaScript, we can have a regular expression like var pattern=/(.+:\/\...

   JavaScript,URL,regular expression, Hostname     2012-06-15 09:16:45

  Why to Build Modern Web Apps with ASP.NET?

ASP.NET offers multiple options for fabricating cloud-based web applications. Its features such as the ability to cope up with different platforms including Mac, Linux, and Windows along with its open source nature indicate its efficiency. The various architectural modifications in the core framework have made the system more affable, and modular components make the job easier by simplifying the various implications.  Microsoft has worked on the roots of this software to render a sophistica...

   WEB DEVELOPMENT,ASP.NET DEVELOPMENT, WEB APPLICATION DEVELOPMENT,.NET DEVELOPMENT     2016-01-25 03:43:26

  Access control in Java -- doPrivileged

Previously we have introduced how Java performs permission check to protect resource access. What if sometimes we need to give some class the temporary access to some resource which it initially doesn't have? AccessController provides six doPrivileged methods to fulfill this requirement. These six methods have below signatures : static T doPrivileged(PrivilegedAction action)static T doPrivileged(PrivilegedAction action, AccessControlContext context)static T doPrivileged(PrivilegedExceptionA...

   JAVA,SECURITY,DOPRIVILEGED     2016-03-08 05:46:42

  Remote execute command in Java example

Frequently there is a need to logon to a remote system and run some commands or programs to get the output, many software can serve this purpose such as putty and gitshell.These software usually provide secure access to the remote system. But have you ever wondered what to do if you need to run commands on many different systems at the same time and get all these results back at a single place? Especially in big data era, many tasks may run on different distributed systems and you want o have a ...

   JSch, Example, Distributed system, SSH2     2014-12-12 03:20:19

  Handling Chinese Character Encoding Issues in Oracle Database

When working with Chinese data in Oracle databases, character encoding issues often lead to garbled text, preventing proper display and processing. This is typically because the default character set in Oracle is US7ASCII, which cannot recognize Chinese characters. By modifying the character sets of the database, client, and application, data can be converted to the correct character set, thus avoiding garbled text issues. This article introduces several methods to resolve Chinese character enco...

   ORACLE,CHINESE CHARACTER,UNICODE,DATABASE     2024-07-12 21:09:14

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