Building a Specific Module in a Maven Multi-Module Project

In a Maven multi-module project, compiling all sub-modules can be achieved using mvn compile in the parent project. However, challenges arise when running specific commands for individual sub-modules.

For example, packaging a war for project B in a project with sub-modules A, B, and C (where both B and C depend on A) results in errors due to missing dependencies.

To address this, Maven provides advanced reactor options:

• -pl, --projects: Build specified reactor projects instead of all projects
• -am, --also-make: If a project list is specified, also build projects required by the list

Best Practice

To package project B along with its required modules, use the following command in the parent project directory:

mvn install -pl B -am

This command will build project B and all modules on which it depends. Note that if the project's artifactId differs from the directory name, the colon syntax should be used, as in:

mvn install -pl :B -am