Henrik's blog



Die Mengenlehre ist ein grundlegendes Teilgebiet der Mathematik, das sich mit der Untersuchung von Mengen, also von Zusammenfassungen von Objekten, beschäftigt. Sie ist für viele Bereiche in der Mathematik und Informatik von großer Bedeutung. Im Bereich der Informatik ist es z.B. für die Definition von kontextfreien Grammatiken wichtig.

Context Free Grammars


A context-free grammar (cfg) is a formal grammar in which exactly one nonterminal symbol is derived on an arbitrarily long sequence of other symbols. They are important for programming languages, because their syntax is described by a cfg.


A context-free grammar $G$ is a 4-tuple $(N, T, P, S)$ with the following features:

Carbon Controller Library


LibGDX contains an extension for controller support, but handling different kinds of controllers isn't so easy. This is caused by the different mappings. The A-button on a Xbox 360 controller has a different code than the A-button on an Ipega controller. The Ipega also has different codes on different platforms. The arbitrary codes are also har to remember.

Audacity damaged project file


Audacity is a free, platform independent, open-source software for audio recording and editing. Computer crashes are always annoying, but especially when you're recording something. This tutorial will show you how to repair a damaged audacity project file.

Java Generics


Generics are a facility of generic programming that were added to Java within version 5. The core idea behind these parameterized types is the addition of so called Type Variables. They allow a type or method to operate on objects of various types, while providing compile-time safety.

Ipega Controller Mappings


The Ipega Bluetooth Controller is a cheap controller for nearly every bluetooth device. With it's holder it is specifically designed for smartphones. The controller has different operating modes, with different behaviors on different platforms. In this tutorial I will show you how to use this controller and it's mapping for LibGDX.

LibGDX Controller


Today we are going to look at the LibGDX Controller extension. I will show you how to add controller support, specifically support for the XBox 360 controller, because it seems to be a widely used gamepad.

Android Battery Monitoring


For many applications, it might be interesting to know the current charging state of our battery. If it is almost empty, you should consider to change into a mode with lower energy consumption. Or you could do it the other way around. If your device is in charging mode, you could consume more resources and power as in normal mode.

Communication between Wearable and Smartphone


In the last tutorial we've learned how to add a configuration activity for a watchface. Now we want to learn how to send settings from a mobile app to the watchface.

Watchface Handheld Settings


In the last chapter of this tutorial series, we learned how to add a configuration activity for a wearable device. Now we want to configure the watch from our handheld app. So we can add quiet complex configurations.


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