Principal Software Engineer/Architect, motorcyclist, drummer, and artist
In some instances you cannot reproduce a failure or condition running a test in an IDE that manifests itself when you run it on your build server or via maven on the command line.
In that case, it is very helpful to be able to remotely attach your IDE to the running maven process and then step through the code.
To do so you will need to:
Execute maven on the command line as follows (adding any additional -D args → Continue reading “Debugging Maven Tests by Connecting an IDE to the Maven JVM”
If you are attempting to use jmap or another Java memory analysis tool to connect to a running JVM to generate a heap dump, even when running jmap as the same user as that of the running process, and encounter the following error:
Attaching to process ID 2712, please wait...
Error attaching to process: sun.jvm.hotspot.debugger.DebuggerException: Can't attach to the processFollowing is the (likely) solution to your problem.
It is likely that the ptrace_scope setting for your system is set → Continue reading “Error attaching to process: sun.jvm.hotspot.debugger.DebuggerException: Can’t attach to the process [SOLVED]”
By default maven sets the compiler version for you. Of course, you can always set it in the pom, but there are cases where you cannot modify the pom, and/or you might want to test compilation and tests with different versions of java.
Following are the specific arguments to pass the compiler version to maven from the command line:
mvn clean install -Dmaven.compiler.source=1.7 -Dmaven.compiler.target=1.7From Joshua Bloch’s Effective Java, 2nd Edition.
A good read for any Java programmer.→ Continue reading “An Excellent Article on finalize in Java”
I have just finished releasing my first project to Maven Central Repository and wanted to capture my notes for the setup of the project and all of the steps required.
You will need an account to the sonatype JIRA for OSSRH. From there, you can request the creation of a new project. See http://central.sonatype.org/pages/ossrh-guide.html for details.
http://central.sonatype.org/pages/working-with-pgp-signatures.html
Create a set of PGP keys
gpg2 Following is how to set-up your environment to be able to set breakpoints, step-through, and debug your MapReduce code in Eclipse.
All of the this was done on a machine running Linux, but should work just fine for any *nix machine, and perhaps Windows running Cygwin (assuming that you can get Hadoop and its naitive libraries compiled under Windows).
This also assumes that you are building your project with maven.
Install a pseudo-distributed hadooop cluster on your development box. (Yes, → Continue reading “Debugging MapReduce MRv2 Code in Eclipse”
When writing unit tests to cover your entire program you will undoubtedly come across the need to test private methods. There are arguments that these methods should be tested via integration tests, but there are sometimes when it makes more sense to test all of the permutations in a unit test. This can be achieved using reflection in Java JUnit tests.
What is a little tricky, and was not completely obvious, was how to use reflection to test a private → Continue reading “Unit Testing Private Static Methods With Primitive Array Arguments”
Following are two basic settings (I believe that there are other language specific, C++ for instance, settings as well).
For Java:
Window->Preferences->Java->Code Style->Formatter->
Click on ‘New’ to create a new profile and select the profile that you want to copy
Then click ‘Edit’ and select ‘Spaces Only’ from the ‘Tab Policy’ dropdown.
You can further set the indentation and tab size.
For default text editor:
Window->Preferences->General->Editors->Text Editors->Insert spaces for tabs→ Continue reading “Configuring Eclipse to Replace Tabs with Spaces for Indentation”
I am doing some refactoring on a Spring MVC application, pulling out configuration data and login crentials from the spring.xml file.
What I want to do is to consolodate sensitive data into external .properties files that can be read, at runtime by the app and not require recompiling the war to make changes.
Thanks to Ben Northrop and Summa Technologies for such a clear, concise and well written article.
The long and the short of it (copied from the → Continue reading “Excellent Example and Explanation on How to Inject Properties from an External Properties File from Outside of a WAR in a Spring Application”
I set up a development instance of Jetty on my local machine and have been happily coding, compiling and deploying via a shell script. The script copies the war from my user’s target directory to the jetty users’s home dir changes the permissions and then moves it to the /webapp dir creating a symlink to the name of the .war that is referenced in a number of config files.
This was working just fine until I did a merge with → Continue reading “Do Not Use Symlinks in Jetty’s webapps Directory”