Creating a generic array in Java

Generic array initialization Recently I work with CompletableFutures. I used the allOf method which takes a varargs as input. Based on the request, a couple of things had to be processed. So how do I create a generic array that I could use at CompletableFuture.allof()? Array.newInstance together with toArray() does the trick. This is my […]

Echo your REST calls with a echo service

Echo services are a simple tool for developing and testing When you implement a service are often in a situation where you have to call another web service, for example service B. And to complicate the situation, service B is not fully implemented or even not available. Than an echo service could make sense for […]

Counting active accounts with Metrics

Based on a request parameter in a servlet context Recently I had the task to report active accounts based on http requests. Here I’m going to show you my solution with Dropwizard Metrics. Basically I am using a servlet filter togehter with an counter. Each account has its own counter. So I have a ConcurrentHashMap […]

Update your package dependencies

So why should I update the deps for my application? Keeping your dependencies up-to-date is more important than ever One reason is that if you update the dependencies regularly than you can do painless migrations. Nearly every 6 months major releases of frameworks e.g like angular or react with API breaking changes are available. And such a […]

Workaround – No tests found with Testrunner JUnit 5

Java 8, Eclipse, JUnit 5 & Gradle It seems to be a bug in Eclipse and it’is fixed in the Oxgen Release 3 (4.7.3). But I still have the problem in my Java 8 project. So I did a little trick. I changed the version for the engine and the launcher back to 5.1.0. Now, […]

Calculate memory usage of Java objects

With Twitter’s ObjectSizeCalculator If you are looking for an easy way to estimate the object size than this could interest you. The memory size of your object depends on the architecture, the actual vm implementation and whether the VM is 32 or 64-bit. ObjectSizeCalculator supports only the Hotspot JVM. For more information see the javadoc ObjectSizeCalculator. […]


This tool is great! I came across SDKMAN in a Spring tutorial. It’s a tool like rvm which helps you to manage parallel version of a SDK for the JVM like: * Java * Gradle * Groovy * Kotlin * Maven * Scala * Spring Boot * Vert.x It’s what compelling, so I installed it […]

Embedded Jetty with Servlet and Annotations

How do I programmatically configure Jetty that I can use Servlet Annotations? If you doing just servlets with jetty, this article could be interesting for you. I show you how I did it. Here comes the configuration: And I defined the following dependencies in build.gradle. That’s all. Hope this helps! Here is the link to […]

Why you should use new language features

A quick list I put together a list with a number of reasons why you should use new language features. The list includes points which are obvious, I learned or I found on the internet. improved design * easier to understand * easier to change * less defects effectiveness * using standards * getting help […]

Every push a build with Travis CI

Build and test your software projects automatically I wanted that cool build passed badge for my projects as I have seen at Github. So I had a look at Travis CI, which is a continuous integration service used to build and test software projects. Let’s have a look at the build file. .travis.yml That’s it. […]