Master Maven Version Management with BOM: Streamline Your Java Projects

Managing project versions and structuring Maven modules can be challenging, but using a parent POM with shared properties and a Maven BOM simplifies the process.

Define a top‑level parent module (e.g., <groupId>com.pilot.basic</groupId>, <artifactId>basic-parent</artifactId>) and set a ${revision} property for the version. Child modules inherit this version, allowing you to omit explicit groupId and version entries.

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <groupId>com.pilot.basic</groupId>
    <artifactId>basic-parent</artifactId>
    <version>${revision}</version>
    <packaging>pom</packaging>
    <properties>
        <revision>1.0.0-SNAPSHOT</revision>
        <java_source_version>1.8</java_source_version>
        <java_target_version>1.8</java_target_version>
        <file_encoding>UTF-8</file_encoding>
    </properties>
</project>

Child modules reference the parent with <parent> and inherit ${revision}, ensuring consistent versions across the hierarchy.

<project>
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.pilot.basic</groupId>
        <artifactId>basic-parent</artifactId>
        <version>${revision}</version>
        <relativePath>../pom.xml</relativePath>
    </parent>
    <artifactId>basic-service</artifactId>
    <packaging>pom</packaging>
</project>

When releasing to a Maven repository, updating the single ${revision} property in the parent POM updates all module versions.

BOM (Bill of Materials) is a Maven feature that defines a set of compatible dependency versions. By importing a BOM, developers no longer need to specify individual versions, and the BOM maintainer ensures compatibility.

Using a BOM helps avoid version conflicts, such as when different transitive dependencies require different versions of the same library, leading to runtime errors like NoSuchMethodError or ClassNotFoundException.

To create a BOM, define a regular POM that only contains a <dependencyManagement> section with the desired dependencies and their versions.

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.pilot.basic</groupId>
    <artifactId>basic-bom</artifactId>
    <version>1.0</version>
    <packaging>pom</packaging>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>druid</artifactId>
                <version>${druid_version}</version>
            </dependency>
            <!-- more dependencies -->
        </dependencies>
    </dependencyManagement>
</project>

To use the BOM, import it in the parent project's <dependencyManagement> with type="pom" and scope="import", then add regular dependencies without versions in child modules.

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.pilot.basic</groupId>
            <artifactId>basic-bom</artifactId>
            <version>${revision}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

When a specific library needs a different version, simply add a <version> element to override the BOM's version.