Apache Maven is a project management tool. Maven performs tasks such as automatic dependency management, project packaging and more. We strongly encourage anyone using OpenIMAJ to use Maven to get their own project started. We’ve even provided a Maven archetype for OpenIMAJ (basically a project template) that lets you get started programming with OpenIMAJ quickly.

OpenIMAJ requires Maven 2 or 3; if you want to build OpenIMAJ from source you will need Maven 3. You can check if you have Maven installed already by opening a terminal (or DOS command prompt) and typing:

mvn -version

If Maven is found the, version will be printed. If the version is less than 2.2.1, or Maven was not found, go to http://maven.apache.org to download and install it. Once you’ve installed Maven try the above command to test that it is working.

To create a new OpenIMAJ project, run the following command:

mvn -DarchetypeCatalog=http://maven.openimaj.org/archetype-catalog.xml archetype:generate

Maven will then prompt you for some input. Firstly, when prompted, choose the openimaj-quickstart-archetype and choose the latest version. For the groupId, enter something that identifies you or a group that you belong to (for example, I might choose uk.ac.soton.ecs.jsh2 for personal projects, or org.openimaj for OpenIMAJ sub-projects). For the artifactId enter a name for your project (for example, OpenIMAJ-Tutorial01). The version can be left as 1.0-SNAPSHOT, and the default package is also OK. Finally enter Y and press return to confirm the settings. Maven will then generate a new project in a directory with the same name as the artifactId you provided.

The project directory contains a file called pom.xml and a directory called src. The pom.xml file describes all of the dependencies of the project and also contains instructions for packaging the project into a fat jar that contains all your project code and resources together with the dependencies. If you find that you need to add another library to your project, you should do so by editing the pom.xml file and adding a new dependency. The src directory contains the code for your project. In particular, src/main/java contains your java application code and src/test/java contains unit tests.

The default project created by the archetype contains a small “hello world” application. To compile and assemble the “hello world” application you cd into the project directory from the command line (replacing OpenIMAJ-Tutorial01 with the name of your project):

cd OpenIMAJ-Tutorial01

and run the command:

mvn assembly:assembly

This will create a new directory called target that contains the assembled application jar (the assembled jar is the one whose name ends with -jar-with-dependencies.jar). To run the application, enter:

java -jar target/OpenIMAJ-Tutorial01-1.0-SNAPSHOT-jar-with-dependencies.jar

The application will then run, and a window should open displaying a picture with the text “hello world”. Closing the window, or ctrl-c on the command line, will quit the application.