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  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

  Why so many Python web frameworks?

When asked about the plethora of web frameworks for Python the answer is often that it is way too easy to put together one in Python. That certainly seems plausible since there are so many libraries that implement the components of a web framework and if it's easy to plug those pieces together then maybe that lowers the bar of entry for new frameworks. So let's give it a shot, we'll pick some components and spend a couple hours seeing how far we can get building a web framework, which we...

   Python,Web framework,Dynamic scripting language,Web design     2012-02-13 05:32:48

  Concise bash programming skills

The following are some concise bash programming skills which we may need in our daily programming work. 1. Check status of command execution The usual way: echo abcdee | grep -q abcd   if [ $? -eq 0 ]; then echo "Found" else echo "Not found" fi Concise way: if echo abcdee | grep -q abc; then echo "Found" else echo "Not found" fi Of course you can remove if...else with following code [Sun Nov 04 05:58 AM] [kodango@devops] ~/workspace $ echo abcdee | grep -q ...

   bash, skill,tip     2012-11-06 10:38:42

  You know what UTF-8 is when you see it?

When we are coding we may often see some encoding specifications in our source codes such as UTF-8,GB2312. Do you know what these encoding mean and why we need them? In this post, Julián Solórzano will introduce the most widely used encoding specification around the world accomodating all different character sets in the world. UTF-8 is a method for encoding Unicode characters using 8-bit sequences. Unicode is a standard for representing a great variety of characters from many ...

   UTF-8,Encoding     2014-04-18 22:13:44

  iPhone App Development: What’s New For Developers In iOS 11

A curiosity ends with the introduction of iOS 11 on 5th of June 2017. It is the next-generation version of iOS. This update takes the best and most advanced operating system and turns it up to 11. But with iOS 11 was released to the public on 19 September 2017 and since then, there have been two distinct updates to iOS 11.02 which fixed the earpiece noise during phone calls; and the major iOS 11.1. iOS 10 was an operating system update that largely ignored the iPad, but Apple made up for it in ...

   APPLE,IOS11     2017-11-02 11:15:22

  Walking through doorways causes forgetting, new research shows

We’ve all experienced it: The frustration of entering a room and forgetting what we were going to do. Or get. Or find.New research from University of Notre Dame Psychology ProfessorGabriel Radvansky suggests that passing through doorways is the cause of these memory lapses.“Entering or exiting through a doorway serves as an ‘event boundary’ in the mind, which separates episodes of activity and files them away,” Radvansky explains.“Recalling the decision...

   Memory loss,Doorway,Forget,Advice     2011-11-21 10:11:19

  How big is sizeof structure?

First let's see the codes of a structure: struct node{ int a; int b; }; Question : What's sizeof(node)? The answer is very simple, on a 32 bit machine, an int will take 4 bytes and two ints will take 8 bytes. So sizeof(node) is 8. The answer for the above codes is 8, then how about the following structure: struct node{ char a; int b; }; Question : Then what's sizeof(node) now? int takes 4 bytes, char takes 1 bytes, is the answer 5? Now the answer may not be 5, on some mac...

   Data structure alignment, pack     2012-10-29 12:13:37

  Understanding Twitter Bootstrap 3

On 27, July, Twitter Bootstrap 3 RC 1 was released, if there are no major bugs found in this release, then it will be the final released Twitter Bootstrap 3 with some minor changes. What changes does Bootstrap 3 have compared to Bootstrap 2? After checking the documents, we can find that there are mainly 3 changes. Embrace flat design In Bootstrap 3, it begins to embrace flat design. First from the official webpage of Bootstrap 3, we can find elements are flat designed. Also, all buttons have no...

   Bootstrap 3,Change,Bootstrap 2     2013-08-05 07:06:22

  Bionic Office

Well. That took rather longer than expected. We have, finally, moved, into the new Fog Creek office at 535 8th Avenue, officially ten months after I started pounding the pavement looking for a replacement for my grandmother's old brownstone where we spent our first few years, working from bedrooms and the garden. Most software managers know what good office space would be like, and they know they don't have it, and can't have it. Office space seems to be the one thing that nobody can get rig...

   Work place,Life,Office,Confortable     2012-01-18 09:00:55

  LEFT OUTER JOIN with ON condition or WHERE condition?

The difference is subtle, but it is a big difference. The ON condition stipulates which rows will be returned in the join, while the WHERE condition acts as a filter on the rows that actually were returned.Simple example: Consider a student table, consisting of one row per student, with student id and student name. In a second table, a list of grades that students have received, with student_id, subject, and grade. Give me a list of all students, and show their grade in Math. This requires a LEF...

   SQL,Outer jo0in,On,Where,On vs where,where vs on     2011-11-01 02:04:29

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