Different modes for H2 Database Engine for testing

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When testing software that requires a database for persisting data there are different ways to do this. One way is to use a real database engine instance for testing purpose only. Setting up a full scale database server is totally oversized for testing purpose. So using a dedicated simply to use database is a good way. Furthermore the data may not persisted as after the test the data is not necessary anymore. For performance reasons a non-persistent database engine would be great. There are many solutions for in-memory database testing. One of them is H2. Let’s have a look how H2 can be configured for this purpose. Continue reading →

Compressed Memory

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When using swap the system is going to be dramatic slow and maybe hangs for seconds as the performance of the next level memory is dramatically slower then random access memory. In case there is not enough physical RAM and swapping happens really often, there is a way to compensate this approach a little bit by using compressed in-memory swap space. Continue reading →

How to use regex groups in Java with ease

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When searching for a pattern or a group of data while processing text in Java, regular expressions are a useful instrument to work with. Using regular expressions in Java, it is possible to identify data in a subset of other data. E.g. when having a number of groups or when developing a regular expression it might be helpful in case you don’t have to know the position of the group in context of the regular expression. For this purpose there is a feature called named capturing group. Continue reading →

Redirecting embedded jetty log to log4j2

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When using embedded jetty within an application, per default there is no support for log4j2. Using slf4j it is possible to redirect the logging to log4j2. But without this redirection there is no way to directly use it. But of course there is a way to use it. Only a piece of simple adapter code is required. Continue reading →

Adding new resolution to the X window server

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When running Debian Linux with VirtualBox there is limited support for high display resolutions. Per default a maximum resolution of 1024x768 is possible. For a modern operating system this resolution is definately not state of the art.

But there is a way to support a higher resolution than 1024x768. It is possible to switch to a resolution like 1920x1080 or more. Even more than one display is possible. Continue reading →

Completely cleaning up git workspace

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When developing software using git as version control system, sometimes there is the wish to completely reset your workspace, so that your snapshot is exactly as the snapshot in the repository. There shall no deleted, missing or additional files or folders that are not tracked. Furthermore git does not track folders. There shouldn’t any dead folders that git doesn’t care for. Let’s have a look how to do that. Continue reading →

Installing Chrome / Streaming Netflix on Ubuntu

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Currently using legal video streaming is a quite tough topic. As drm mechanism prevent most of the users to use legal video streaming on Linux. I don’t want to make some advertisement, but using Amazon Prime/Instant Video, Google Play, Netflix etc.. is not working out of the box. But Netflix provided a way to use Google Chrome for streaming. Continue reading →

Running Junit tests in a specific order

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When running tests with Junit, per default the test execution order is deterministic. But the order of all the tests is not predictable. But for some reasons, it may be useful to ensure a specific order. E.g. one of your tests is sometimes failing and you have no idea. So maybe your production code is not threadsafe or there are some other effects that influence your test without knowing it. E.g. a cache that is filled with some results by a test running before. Continue reading →