The latest expert opinions, articles, and guides for the Java professional.

Automated performance regression testing

What do buying a fire extinguisher and not smoking inside the house have in common? Both are aimed at mitigating the effects from a potential fire. The important difference is that one measure is proactive, and the other is reactive. Same applies to performance: monitoring reacts to damage and testing prevents damage.

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Spring Framework Annotations cheat sheet

This post continues with the series of the cheat sheets that we’ve been producing all year. And this time it’s all about Spring Framework annotations. We look at the annotations that make Spring a flexible, but at the same time a very stable choice of a framework.


You can find tons of tutorials about how you should use Spring — its configuration and a myriad of excellent Spring projects on the internet. We, however, want to provide a one-page reference for the most commonly used annotations. With this, you will always remember which annotations go where. Here we go!

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XRebel 3.1.4 Comes with Couchbase Integration!

We believe Couchbase is one of the most popular and widely adopted NoSQL data storages.

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JRebel for Android 2.0!


Today, I’m excited to announce a significant milestone in the development of JRebel for Android. JRebel for Android has reached the 2.0 status. This is the first major release we have introduced since the release of JRebel for Android v1.0 in December last year.

We have been listening to your feedback and turned it into features that will help JRebel for Android make your development process faster and simpler. Literally, hundreds of fixes and improvements have been added in the v2.0 release.

In this post, I want to shed some light on the main features we’ve added since v1.0 and why we think it’s a really big deal.

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Spring vs Java EE: Which is More Popular?

A couple of months ago, we released our annual Developer Productivity Report, where we looked at the results of asking Java developers about what tools and technologies they use. Among all kinds of cool findings, like what IDE is the most popular, whether microservices offer a salvation from solving hard problems, and so on, we got the data about the web frameworks our respondents use.


We saw that both Spring and Java EE are pretty popular choices, and the general consensus is that both are quite excellent. That realization made us ask a deeper question. What components of the platform do you actually use?

In this post we analyze the data we gathered to answer that question

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Speeding up Android builds with an incremental Java compiler

Since we launched JRebel for Android last year, we’ve learned a lot about the Android build system, how it behaves in real-world projects, and where actual build time bottlenecks occur. Most of this invaluable feedback came from our JRebel for Android users and provided us ideas on how to make it even faster!

Today, I’m pleased to announce that the JRebel for Android now includes an incremental compiler that makes the performance of code and resource updating even snappier.

When you use the default toolchain, specifically Android Studio and Gradle, there are two major tasks in the build process of an Android app that are not entirely incremental. First is the compilation of Java source files and the other is resource packaging. In this post, I wanted to share some details about the compilation aspect and how we made it incremental, what challenges still exist and where it can take you performance wise.

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Java 8 Puzzlers: The Strange, the Bizarre, and the Wonderful with Baruch Sadogursky and Viktor Gamov

RebelLabs is the media partner for the Virtual JUG, the online Java User Group which brings you the best sessions by world class speakers. The best part? You don’t have to leave your house or office to enjoy them! You can educate yourself and become a better developer even from the comfort of your home!

This time I want to recap a magnificent session we had just recently: “Java 8 Puzzlers: The Strange, the Bizarre, and the Wonderful”. The speakers who brought it to our screens are two established experts in the Java community: Baruch Sadogursky and Viktor Gamov.

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JUnit 5: Next Generation Testing on the JVM with Nicolai Parlog

Well, if for the last ten years you haven’t been living under a rock, or not on the JVM, you probably have at least some experience with JUnit. You’ll know it’s the most used library to write unit tests in for Java projects.

JUnit is quite mature and is pretty good as libraries go, however recently, after the release of the JDK 8, the JUnit team worked hard and delivered a major rewrite of the test engine. One of the main syntactical reasons was to adopt lambdas, so you can write code that is full of them and benefit from unit tests that use a similar code style. However, the differences between JUnit version 4 (or older, if you’re still half under the rock) and the fresh version 5 do not stop there.

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The Developer’s Guide to Java Performance Tuning

Good developers care about performance. However, even the best developers don’t realize that performance tools are not a one-size-fits-all type deal, rather they’re components in a suit of armor. You see, a suit of armor has many pieces – a breastplate, a helmet, gauntlets, etc. – all of which are designed specifically for different parts of the body. We’ll be defining 4 major types of performance tools and which areas of the (figurative) body they’re designed for, and finally, honing in on the solution best suited for development.

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JUnit Cheat Sheet

This post continues our series of the most useful and beautiful cheat sheets from which software engineers can learn the most frequently used commands, idioms, and best practices on various topics.

Today, we’re talking about unit tests and JUnit, one of the most popular unit test libraries in the JVM ecosystem, including some of the really useful updates in JUnit 5, which brings the library up to speed with the new features in Java 8. Now, it’s very tempting to just grab the image, print it out and start looking for a place on the wall to pin it up. By all means, do it! But make sure you stay with us, and continue reading this post, as we’ll explain the content of the cheat sheet in much more depth. The cheat sheet will then serve as a visual hint for your future testing.

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