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A Wonderful SQL Feature: Quantified Comparison Predicates (ANY, ALL)


Have you ever wondered about the use-case behind SQL’s ANY (also: SOME) and ALL keywords? You have probably not yet encountered these keywords in the wild. Yet they can be extremely useful. But first, let’s see how they’re defined in the SQL standard. The easy part:           8.7 <quantified comparison predicate> Function Specify a quantified comparison. ...

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The most important factor in software decay


Do you have big balls of mud? Here’s an experiment to amaze your friends. You probably listen to music on your phone via some sort of headset. The headset we shall consider here consists of two earbuds (in-ear pieces, rather than head-phones which cover the ears) connected via wires to a jack which plugs into the phone itself. Disconnect your ...

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Autoboxing, Unboxing, and NoSuchMethodError


J2SE 5 introduced numerous features to the Java programming language. One of these features is autoboxing and unboxing, a feature that I use almost daily without even thinking about it. It is often convenient (especially when used with collections), but every once in a while it leads to some nasty surprises, “weirdness,” and “madness.” In this blog post, I look ...

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The Emergence of DevOps and the Fall of the Old Order


Software Engineering has always been dependent on IT operations to take care of the deployment of software to a production environment. In the various roles that I have been in, the role of IT operations has come in various monikers from “Data Center” to “Web Services”. An organisation delivering software used to be able to separate these roles cleanly. Software ...

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Publish JAR artifact using Gradle to Artifactory


So I have wasted (invested) a day or two just to find out how to publish a JAR using Gradle to a locally running Artifactory server. I used Gradle Artifactory plugin to do the publishing. I was lost in endless loop of including various versions of various plugins and executing all sorts of tasks. Yes, I’ve read documentation before. It’s ...

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The dark side of Hibernate AUTO flush


Introduction Now that I described the the basics of JPA and Hibernate flush strategies, I can continue unraveling the surprising behavior of Hibernate’s AUTO flush mode. Not all queries trigger a Session flush Many would assume that Hibernate always flushes the Session before any executing query. While this might have been a more intuitive approach, and probably closer to the ...

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Understanding volatile via example


We have spent last couple of months stabilizing the lock detection functionality in Plumbr. During this we have stumbled into many tricky concurrency issues. Many of the issues are unique, but one particular type of issues keeps repeatedly appearing. You might have guessed it – misuse of the volatile keyword. We have detected and solved bunch of issues where the ...

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JUnit in a Nutshell: Hello World


JUnit seems to be the most popular testing tool for developers within the Java world. So it is no wonder that there have been written some good books about this topic. But by earning a living as consultant I still meet quite often programmers, who at most have a vague understanding of the tool and its proper usage. Hence I ...

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Saving to a SQLite database in your Android application


This is the fourth post in my series about saving data in Android applications. Here are the other posts : Introduction : How to save data in your Android application Saving data to a file in your Android application Saving preferences in your Android application The previous posts described how to save files to the file system and to the ...

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Understanding JUnit’s Runner architecture


Some weeks ago I started creating a small JUnit Runner (Oleaster) that allows you to use the Jasmine way of writing unit tests in JUnit. I learned that creating custom JUnit Runners is actually quite simple. In this post I want to show you how JUnit Runners work internally and how you can use custom Runners to modify the test ...

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