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java.lang.reflect.MalformedParameterizedTypeException exception in Grails when using HttpBuilder

Recently I encountered really nasty error in grails which took quite some time to fix. It was really hard to find reason because of the really weird stacktrace and it was only happening when being deployed on tomcat server. Exception looked something like this: First it seem to have something to do with log4j system, but it turns out that HttpBuilder was to blame! It has different version of groovy specified as dependency, which was conflicting with version of groovy coming with grails, causing this nasty error.

Grails locking rows for update in PostgreSQL with NOWAIT

One day I needed to lock a record in grails application for update so other transactions does not mess with it while I am updating it. I started digging through the doc and found a section about locking in official documentation. It was pretty straightforward: you just need to use *lock() *method. So I did this: And this was working fine. In this basic case. My actual scenario was more complicated, it involved constantly polling database for new messages to process which are not been taken by other workers.

Why test driven development works

This post will be not about technical stuff of Android or Grails, but about programming in general. Yesterday, when I was waiting for my program to start on android I start thinking that I lose quite some time for this start-click-see result cycle. If it takes 30-50 seconds to build upload and start new apk on android, then it can easily end up as half an hour a day just restarting the app.

Speak the code application on Google play

Recently, when I was going through 2-step verification process for my gmail account, I thought that it would be nice if I did not have to peek my phone and check the text. If there would be an app just to read that code out loud so I can enter it. So, I created it! It is now on google play and you can download it to your android phone here: speak the code

Protobuf and optional values

Just small note to all you guys if you are using google protobuf library for communicating with server. Lets say you have simple protobuf message with one optional numeric field: If you are using some dynamic language in your server backend, you can end up having code like this: Now question, what value of limit variable will be, if message will not have limit field set? Answer is: 0.

Executing scheduled periodic tasks in Android

I think that Android is a platform created by developers for developers. That’s why sometimes it offers several different ways to do the same thing. Let’s say you want to execute some periodic task in background, even if currently none of your Activities is active. How you can achieve this? First of all, you should be careful with Application process lifecycle. Basically, if none of your activities are visible, Android will destroy your app at some point in the future.

Parsing HTML pages like a boss with Groovy

Remember I told you that Groovy is really good for scripting? Time for some proof. Lets say you want to download and parse some html page and get the content of the third list on page. How do you do that? Using URL and Regular expressions? Here I`ll tell you how it can be done in groovy. I will use gumtree search result as an example: // Grap HTTPBuilder component from maven repository @Grab(group='org.

Couple words about Groovy

Before I introduce *Grails *to you, I want to write a little bit about Groovy, because it is used as the main language in grails. What is Groovy? Groovy is a dynamic language build on top of Java Virtual Machine whose features are inspired by the success of languages like Python, Ruby and smalltalk. Lets go forth step by step. Groovy is a language for Java Virtual Machine What does that mean?

Grails Class.forName ClassNotFoundException

Hi everybody. While I am writing introduction post about grails, I would like to share solution for a problem I have encountered today. Lets say inside Grails application you want to get a Class object for some Groovy/Java class, which is located in src/groovy or src/java folders by class name. For example, in BootStrap.groovy. You might end up with code like this: // Somewhere in BootStrap.groovy def obj = Class.forName("com.binarybuffer.grails.MyCoolClass") You may find that this code throws ClassNotFoundException.

Things you need to remember when using finally in Java

Because Java has a Garbage collector and you don’t know for sure when your object will be destroyed it is tricky to do proper resource management, in comparison with C++ where objects are created on the stack or you control their lifecycle manually by new/delete operator. To help you deal with that, the finally block was introduced. Assume you have some kind of resource: package com.binarybuffer.tests.trycatch; /** * Class that simulates some resource which needs to be released.