The project this time will contain many modules. We will still use Maven in this chapter. We will set up a so-called multi-module project in Maven. In such a project, the directory contains the directories of the modules and pom.xml. There is no source code in this top-level directory. The pom.xml file in this directory serves the following two purposes:

• It references the modules and can be used to compile, install, and deploy all the modules together
• It defines parameters for the modules that are the same for all of them

Every pom.xml has a parent and this pom.xml is the parent of the pom.xml files in the module directories. To define the modules, the pom.xml file contains the following lines:

<project> 
... 
    <modules> 
        <module>SortInterface</module> 
        <module>bubble</module> 
        <module>quick</module> 
    </modules> 
</project>

These are the names of the modules. These names are used as directory names and also as artifactId in the pom.xml module. The directories in this setup look as follows:

$ tree 
   |-SortInterface 
   |---src/main/java/packt/java9/by/example/ch03 
   |-bubble 
   |---src 
   |-----main/java/packt/java9/by/example/ch03/bubble 
   |-----test/java/packt/java9/by/example/ch03/bubble 
   |-quick/src/ 
   |-----main/java 
   |-----test/java