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JavaLand 2018

JavaLand 2018

JavaLand Logo Disclaimer: I may be a bit biased on the topic as I really like the conference from the beginning and attended in this years session review process.
The 2018 edition of the still very young, community driven, Java conference JavaLand took place in the theme park “Phantasialand” in Brühl next to Cologne from March 13th-15th. The conference was splitted into two conference days (13th and 14th) and one workshop day. It was just the fifth edition of JavaLand and I was able to attend the conference days.
What makes JavaLand pretty special and very unique is the venue. It is not only located in a theme park but as it is early in the year the season for the park has not yet begun and the park is opened for JavaLand attendees only. To be honest they just open up a part of the park but it is still pretty cool. As part of the social event on the first conference day there are some park rides opened for the attendees which shifts the spirit of the attendees pretty fast away from the technical part and makes it really easy to come together with new people even if you are not the type to make new contacts fast.
The conference itself mostly consists of 40 minute talks mixed up with some panels and just a couple of hands on workshops per day.

Sessions:
A huge part of the sessions is in german which should be no surprise as it is a german conference which tries to get new speakers from the community involved and as common as it is that most of us speak and understand english these days it is not the mother tongue and there still are many people who don’t speak english frequently which leads to not being comfortable and practiced enough to hold a talk in english. Nevertheless the program committee has an eye on having some english talks at any time so that non german speaking visitors can attend a session at any time.
This year I could hardly make out any new hype topic in the talks. The topics were nicely spread so there should be something interesting for everyone most of the time.
I for myself attended a lot of core Java topics and listened to some panels about the future of JavaEE/JakartaEE as well as the distribution of the JDK and the changes in the support for desktop technologies.
Besides that I got a nice introduction to gRPC which I only knew by name so far and am now in a better position to sort the application possibilities out.

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Java Forum Nord 2016

Java Forum Nord 2016

Java Forum Nord
Last week (October 20th) I attended the second “Java Forum Nord” in Hannover. The Java Forum is now in its second year but is the evolution of an older and smaller conference in Göttingen (Source Talk Tage). The relocation and renaming of the conference was necessary because it wasn’t possible to attract an audience huge enough to get top speakers to Göttingen. To make the transfer possible the JUG Deutschland which is located in Göttingen and hosted the Source Talk cooperates now with the JUG Bremen, JUG Hamburg, JUG Hessen (Kassel), JUG Ostfalen, SUN User Group Deutschland and the local JUG Hannover.
As a result the conference professionalized very quickly and the audience grew by a huge number. After the first edition in 2015 took place in a small Hotel at the Hannover main train station and was quickly sold out they relocated to the bigger Hotel Dormero in Hannover which had space for 400 participants and was sold out, too. After I would consider last year as a transition year I had this year the feeling to be on a very serious one day conference which had definitively left the amateur status. What makes this conference so special is that it is organized by the JUGs (Java User Groups) and aims for no profit which makes it possible to give very cheap tickets away.

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Using CellUtil with POI to avoid too many cell styles in Excel

Using CellUtil with POI to avoid too many cell styles in Excel

https://poi.apache.org
https://poi.apache.org

When you create Excel documents with the popular Apache POI library it is possible that you encounter a problem where Excel tells you there are “Too many different cell formats”. A possible source for this is that you probably have a loop structure in which you define a new cell style for every cell you create.
poi-cellstyle-loop

Excel is limited in the amount of cell styles it can handle in a single document (4000 per document). Therefore the above code would break. The easy fix would be to define the cell style outside of your loop and reuse it.
But sometimes you want to create different cell styles depending on a line number for example. In this case POI comes with a handy utility class named CellUtil that allows you to modify existing cell styles without creating a new one. Internally it has to create a new cell style and saves it in a map. If you make the same modification at any other place in your code again it will iterate that map, find the previously created style and reuses it. Therefore the same style is only created once. The usage is quite simple and would adapt to the sample above as follows

poi cellUtil

The code above will add a border to the bottom of every second cell created but because it is every time the same modification CellUtil will only create one additional style and apply this every time again.

Die 20-minuten Regel

Die 20-minuten Regel

Ich kann mich leider beim besten Willen nicht mehr erinnern wo es war, aber vor einigen Jahren las ich von der 20-minuten Regel und so skeptisch wie ich vorerst auch war so gut bin ich damit gefahren seit ich sie für mich angewandt habe.

Es geht dabei um das Warten auf Verabredungen bzw. Termine. Ich habe mich früher immer wahnsinnig geärgert wenn man z.B. mit Freunden irgendwo verabredet war und jemand kreuzte nicht auf oder kam erst eine Stunde zu spät. Da ich mit meiner Zeit besseres anfangen kann als zu warten wende ich in solchen Fällen heute immer die 20 Minuten Regel an.

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Fishermans Sparpackungen

Fishermans Sparpackungen

Als ich letztens im Supermarkt war wollte ich noch schnell eine Packung Fishermans Wild Cherry mitnehmen und bin zum Bonbonregal gegangen. Da habe ich dann eine Pappschachtel erspäht die drei normale Fishermans Packungen enthielt. Da man bei sowas bekanntermaßen immer vorsichtig sein muss habe ich eben nochmal nachgerechnet und gesehen das die Dreierpackung auch tatsächlich günstiger war, also habe ich sie gekauft. Als ich jetzt wieder in den SUpermarkt kam und nochmal Nachschub mitnehmen wollte viel mein Blick auf ein kleines Detail das mir beim ersten Mal durchgerutsch war. die Dreierpackung ist doch teurer, da sich in dieser (trotz gleicher Größe) 25g-†20g-†Fishermans befinden. In einer Einzelpackung sind hingegen 30g-†25g-†womit diese dann doch wieder günstiger wird.

Dieses Vorgehen zielt schon derart offensichtlich darauf ab seine Kunden zu verarschen das ich mich echt darüber aufregen könnte. Die Papierverpackungen unterscheiden sich sonst absolut gar nicht, gleiche Größe, gleiches Design nur eben die 5 Gramm weniger. Schöne Supermarktwelt.