Question

I have followed this guide:

http://maven.apache.org/guides/plugin/guide-java-plugin-development.html

I have created a maven-plugin project “hello-maven-plugin” with the pom file:

<project>
  <modelVersion>4.0.0</modelVersion>
  <groupId>sample.plugin</groupId>
  <artifactId>hello-maven-plugin</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>maven-plugin</packaging>

  <name>Sample Parameter-less Maven Plugin</name>

  <dependencies>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-plugin-api</artifactId>
      <version>2.0</version>
    </dependency>
  </dependencies>

<build>
    <plugins>
      <plugin>
        <groupId>sample.plugin</groupId>
        <artifactId>hello-maven-plugin</artifactId>
        <version>1.0-SNAPSHOT</version>
        <executions>
          <execution>
            <phase>compile</phase>
            <goals>
              <goal>sayhi</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

and when I build it with:

mvn install

it prints “Hello, world.” in the console as expected.

I have created another maven project “my-project-usage” where I would like to use the “hello-maven-plugin” plugin. It has this pom:

<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>
  <parent>
    <artifactId>my-project</artifactId>
    <groupId>com</groupId>
    <version>0.0.1-SNAPSHOT</version>
  </parent>
  <artifactId>my-project-usage</artifactId>
  <build>
    <plugins>
      <plugin>
            <groupId>sample.plugin</groupId>
            <artifactId>hello-maven-plugin</artifactId>
            <version>1.0-SNAPSHOT</version>
      </plugin>
    </plugins> 
  </build>
</project>

When I build this project the hello-maven-plugin is never executed, why?

Answer 1

Move this <execution> block from first POM to then second one, because you need plugin’s execution there, where you use the plugin, not in the plugin itself.