Spring boot and maven exec plugin issue

Question

I\'ve created a bare-bone Maven project, completely empty except the pom.xml.

With this pom (note that parent element is commented-out):

Answer 1

Its because Spring-Boot is adding some extra maven configuration to your project. If you are using eclipse, there's a Tab called: 'Effective POM'.

From this tab you can see that it adds this snippet below:

    <plugin>
      <groupId>org.codehaus.mojo</groupId>
      <artifactId>exec-maven-plugin</artifactId>
      <version>1.2.1</version>
      <configuration>
        <mainClass>${start-class}</mainClass>
      </configuration>
    </plugin>

So when you run it with spring-boot as parent, it looks for the value of ${start-class}, which resolves to empty unless you defined it, that's when you see the error about not having a value for the mainClass parameter.

Add this to your project:

<properties>
    <start-class>com.Test</start-class>
</properties>

Then run it: clean compile exec:java

[INFO] --- exec-maven-plugin:1.2.1:java (default-cli) @ springboot-test ---
**********test**************
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.388 s
[INFO] Finished at: 2014-12-05T15:25:05-06:00
[INFO] Final Memory: 17M/231M
[INFO] ------------------------------------------------------------------------

You can also provide the value for the start-class property on the command line, this works even if you didn't define it inside your pom file:

mvn exec:java -Dstart-class=com.Test