Author Archives: Jesper Udby

About Jesper Udby

I'm a freelance computer Geek living in Denmark with my wife and 3 kids. I've done professional software development since 1994 and JAVA development since 1998.

Trying to eat less meat

Meat is a very important part of many peoples meals.
Perhaps we can do with less of it. Continue reading

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FileCache – a simple cache of generated static content

The FileCache sits at the core of the bankopladerne.dk backend with the following responsibilities:

* Ensure often-accessed content is cached.

* Maintain cache of files in the temporary file system while not using too much space.

* Ensure an item is only produced once in a high-traffic scenario where the same resource is requested concurrently. Continue reading

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Bankopladerne.dk upgrade April 2024

Bankopladerne.dk So I have this “hobby site” called bankopladerne.dk. The main purpose is to expose free bankoplader for everybody to use, but there are also some (hidden) features only available to paying customers. The “backend” primarily serves PNG’s and PDF’s … Continue reading

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Binary Search

Wow that is ancient technology you might think – can more be written about that? Probably yes 🙂 So Binary Search has been around for as long as we’ve had sorted lists and the need to locate a specific element … Continue reading

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Mutable

So you might wonder – “Mutable” – what is that all about? In general we prefer things to be Immutable. With immutability comes improved performance because we do not have to copy things around and the JIT can do some … Continue reading

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Generating garbage…

At JCrete the last couple of years I’ve had the pleasure to be socializing with, among others, HFT people like Peter Lawrey and Martin Thompson. Those HFT dudes really makes me thinking when I’m implementing stuff. Thinking about how much … Continue reading

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SafeEquals

I’m currently designing a user-authentication OAuth2 based service. I’m trying very hard never ever to reveal anything about users or passwords. Credential-lookup by userid is always done twice. If the user is not found a known dummy-user is looked up … Continue reading

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YN

Yeah, I know, this isn’t rocket science. But it is rather nice 🙂 So, I’m working on this JEE project, backed by an Oracle database. Some of my work involves refactoring CMP 2.1 entities into JPA entities. Here I’m faced … Continue reading

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Unit testing really simple implementations

As an independent subcontractor (freelance consultant) I get to work in various very different organisations, with very different approaches towards testing in general and unit-testing in particular. Some places unit-testing is mandatory and there might even be a code-coverage tool … Continue reading

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Bad sample code…

Okay, I just HATE bad code. I’m not religious about how you express your business logic in the code. I don’t mind “different” indentation or long methods although I try to keep my own code as short and simple as … Continue reading

Posted in Fun, Java | 1 Comment