How can I create an executable/runnable JAR with dependencies using Maven?

java

maven-plugin

executable-jar

dependency-management

byAlex Kataev·Nov 8, 2024

Embarking on a JAR-venture? Use the Maven Shade Plugin to create a runnable JAR with all dependencies:

Let's get this party started with this pom.xml snippet:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>3.2.4</version> <!-- Don't forget to check for the latest party favors (version)! -->
    <executions>
        <execution>
            <phase>package</phase>
            <goals><goal>shade</goal></goals>
            <configuration>
                <transformers>
                    <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                        <!-- It ain't a party until you plug in the "mainClass"! -->
                        <mainClass>your.package.MainClass</mainClass>
                    </transformer>
                </transformers>
            </configuration>
        </execution>
    </executions>
</plugin>

Replace your.package.MainClass with your full-of-character entry point.
Now start the party (run the command) mvn package in your terminal.

The result: a self-sufficient executable JAR (target/your-artifactId-version-shaded.jar) ready to run wild with java -jar.

Navigating through the JAR-creation maze

It's a JAR out there! Here's a more detailed journey into creating runnable JARs with Maven.

Fork-in-the-road: Choosing the right plugin

One JAR-solution doesn't fit all, so here are more at your disposal:

Maven Shade Plugin: More than meets the JAR, it creates a one-dish JAR, aka "uber JAR" with class relocation for differing dietary preferences (version conflict resolutions).
Maven Assembly Plugin: Packs your JAR lunchbox neatly with separate containers for each (dependency). That's my kind of organized chaos!
Maven Jar Plugin: For those preferring a variety in a single meal (application), it generates a JAR complete with an external buffet of classes (classpath).

Setting the table: Necessary adjustments

Successful JAR packaging requires some kitchen puns (and adjustments too):

Connect your plugin execution to the life of the party (Maven lifecycle):

<executions>
    <execution>
        <!-- 'make-my-jar-with-dependencies' stylized as a haute couture collection -->
        <id>make-my-jar-with-dependencies</id>
        <phase>package</phase>
        <!-- Plugin configuration is a dish best served here -->
    </execution>
</executions>

This ties your packaging with mvn install or mvn package.

Carefully cater to your special guests (files):
- Use the AppendingTransformer for META-INF/services. It's the VIP lounge for service provider/configuration files!
- XmlAppendingTransformer for appetizing XML-files, ensuring no byte goes to waste.

If the JAR fails, check if you've served the correct mainClass and garnished your pom.xml properly.
Conflict resolution: shade plugin's transformers are the solution to any neighborhood disputes (file collisions) among your dependencies.
Always serve your guests the latest and greatest! Confirm that you're using the updated versions of all the plugins.

explain-codes / Java / How can I create an executable/runnable JAR with dependencies using Maven?

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