Maven project version inheritance - do I have to specify the parent version?

EDIT: Since Maven 3.5.0 there is a nice solution for this using ${revision} placeholder. See FrVaBe's answer for details. For previous Maven versions see my original answer below.

No, there isn't. You always have to specify parent's version. Fortunately, it is inherited as the module's version what is desirable in most cases. Moreover, this parent's version declaration is bumped automatically by Maven Release Plugin, so - in fact - it's not a problem that you have version in 2 places as long as you use Maven Release Plugin for releasing or just bumping versions.

Notice that there are some cases when this behaviour is actually pretty OK and gives more flexibility you may need. Sometimes you want to use some of previous parent's version to inherit, however that's not a mainstream case.


Since Maven 3.5.0 you can use the ${revision} placeholder for that. The use is documented here: Maven CI Friendly Versions.

In short the parent pom looks like this (quoted from the Apache documentation):

<project>
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.apache</groupId>
    <artifactId>apache</artifactId>
    <version>18</version>
  </parent>
  <groupId>org.apache.maven.ci</groupId>
  <artifactId>ci-parent</artifactId>
  <name>First CI Friendly</name>
  <version>${revision}</version>
  ...
  <properties>
    <revision>1.0.0-SNAPSHOT</revision>
  </properties>
  <modules>
    <module>child1</module>
    ..
  </modules>
</project>

and the child pom like this

<project>
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.apache.maven.ci</groupId>
    <artifactId>ci-parent</artifactId>
    <version>${revision}</version>
  </parent>
  <groupId>org.apache.maven.ci</groupId>
  <artifactId>ci-child</artifactId>
   ...
</project>

You also have to use the Flatten Maven Plugin to generate pom documents with the dedicated version number included for deployment. The HowTo is documented in the linked documentation.

Also @khmarbaise wrote a nice blob post about this feature: Maven: POM Files Without a Version in It?

Tags:

Inheritance

Maven

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