How can I display a message in Maven

How can I display a message in Maven?

In ant, we do have "echo" to display a message, but in maven, how can I do that?

You can use the antrun plugin:

<plugin>
    <artifactId>maven-antrun-plugin</artifactId>
    <executions>
        <execution>
            <phase>generate-resources</phase>
            <goals>
                <goal>run</goal>
            </goals>
            <configuration>
                <tasks>
                    <echo>Hello world!</echo>
                </tasks>
            </configuration>
        </execution>
    </executions>
</plugin>

One issue though is that you have to choose what phase of the build lifecycle to bind this to (my example has the plugin bound to generate-resources). Unlike Ant, you aren't controlling the lifecycle yourself, but rather just binding plugins to certain points in a pre-defined lifecycle. Depending on what you are actually trying to do, this may or may not make sense for your use case.

You can use Björn Ekryd's Echo Maven Plugin, which is published in Maven Central:

<plugin>
    <groupId>com.github.ekryd.echo-maven-plugin</groupId>
    <artifactId>echo-maven-plugin</artifactId>
    <version>1.2.0</version>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <goal>echo</goal>
            </goals>
            <configuration>
                <message>war has changed</message>
            </configuration>
        </execution>
    </executions>
</plugin>

[INFO] --- maven-war-plugin:2.4:war (default-war) @ mymodule ---
[INFO] Packaging webapp
[INFO] Processing war project
[INFO]
[INFO] --- echo-maven-plugin:1.2.0:echo (default) @ mymodule ---
[INFO] war has changed
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------

Also, this plugin has 95% code coverage, which is pretty cool.

You can use Groovy Maven Plugin for this.

<plugin>                                                         
    <groupId>org.codehaus.gmaven</groupId>                       
    <artifactId>groovy-maven-plugin</artifactId>                 
    <version>2.0</version>                                       
    <executions>                                                 
        <execution>                                              
            <phase>validate</phase>                              
            <goals>                                              
                <goal>execute</goal>                             
            </goals>                                             
            <configuration>                                      
                <source>                                         
                    log.info('Test message: {}', 'Hello, World!')
                </source>                                        
            </configuration>                                     
        </execution>                                             
    </executions>                                                
</plugin>                                                        

The configuration above will produce the following output:

[INFO] Test message: Hello, World!