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How to run a background task in a servlet based web application?

... your job here which should run every 5 seconds. } } Yes, that's really all. The container will automatically pickup and manage it. EJB unavailable? Use ScheduledExecutorService If your environment doesn't support EJB (i.e. you're not using not a real Java EE server, but a barebones servle...
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Differences between action and actionListener

...just specify exactly that string in the action attribute. Thus, this is totally clumsy: <h:commandLink value="Go to next page" action="#{bean.goToNextpage}" /> With this senseless method returning a hardcoded string: public String goToNextpage() { return "nextpage"; } Instead, just put t...
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Aspect Oriented Programming vs. Object-Oriented Programming

...ics need to be updated on screen. Assume to repaint the graphics you must call "Display.update()". The classical approach is to solve this by adding more code. At the end of each set method you write void set...(...) { : : Display.update(); } If you have 3 set-methods, that is not a pro...
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jquery $(window).height() is returning the document height

... With no doctype tag, Chrome reports the same value for both calls. Adding a strict doctype like <!DOCTYPE html> causes the values to work as advertised. The doctype tag must be the very first thing in your document. E.g., you can't have any text before it, even if it doesn't re...
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Why use Ruby instead of Smalltalk? [closed]

...hrough its adolescence. There are a lot of similarities between Ruby and Smalltalk -- maglev is a testament to that. Despite having a more unusual syntax, Smalltalk has all (if not more) of the object-oriented beauty of Ruby. ...
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Best way to add “current” class to nav in Rails 3

...d this thoroughly and I'm very new to RoR (moving over after a decade with PHP) so if this has a major flaw I'd love to hear it. At least this way you only need 1 helper function and a simple call in each link. share ...
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What does “javascript:void(0)” mean?

...rator is often used merely to obtain the undefined primitive value, usually using “void(0)” (which is equivalent to “void 0”). In these cases, the global variable undefined can be used instead (assuming it has not been assigned to a non-default value). An explanation is provi...
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Amazon EC2, mysql aborting start because InnoDB: mmap (x bytes) failed; errno 12

... the crash you may need to setup a swap space for your micro instance. Actually performance wise is better to enable swap. Steps below show how to make a swap space for your Micro instance. I assume you have AWS Account with a Micro instance running. Run dd if=/dev/zero of=/swapfile bs=1M count=102...
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What is normalized UTF-8 all about?

.... Compatibility Normalization Unicode also includes many characters that really do not belong, but were used in legacy character sets. Unicode added these to allow text in those character sets to be processed as Unicode, and then be converted back without loss. Compatibility normalization converts t...
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Is D a credible alternative to Java and C++? [closed]

...of a programming language for real-world software development is only partially related to the quality of the language itself. As a pure language, D arguably has many advantages over C++ and Java. At the very least it is a credible alternative as a pure language, all other things being equal. How...