Mvn compile before exec - maven

Question

I am trying to set up my POM such that when I do mvn exec:exec or mvn exec:java it will first compile the source and iff successful, execute it.
I have the following and have tried moving the <execution> part about but can't get it to work:
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
<executions>
<execution>
<phase>exec</phase>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>1.2.1</version>
<configuration>
<mainClass>my.main.class</mainClass>
</configuration>
</plugin>
</plugins>
</build>
When I do either mvn exec:exec ... or mvn exec:java it doesn't first compile. I have tried putting the <execution> part in the exec plugin section but that didn't work either?

Answer 1

It's an old topic, but someone else might be interested in an alternative solution for this.
It's not exactly what you were looking for, but you can compile and execute using a single command:
mvn compile exec:exec
This way Maven will always compile the project before executing it.

Answer 2

You can bind the exec plugin to a phase following compile in build lifecycle (verify in the example below):
<profile>
<id>proxy</id>
<build>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>1.2.1</version>
<executions>
<execution>
<phase>verify</phase>
<goals>
<goal>exec</goal>
</goals>
<configuration>
<mainClass>my.main.class</mainClass>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</profile>
and than run mvn verify.
I see the answer is very late and you may have found a solution.
I'm just leaving as a reference for others who may need it.

Answer 3

This will not quite answer the question but it will help us to accomplish the main objective you have.
Instead of executing a build goal when running the mvn exec:java we can execute the mvn exec:java when calling a 'post-build" phase/goal.
This will effectively make that phase unusable as it was because we will be substituting it by the execution but if we have a "post-build" goal that we are not using (like package or install) we can use it for the execution like so:
using package goal will end up like:
...
<properties>
...
<main.class>${project.groupId}.MainClass</main.class>
...
</properties>
...
<build>
<plugins>
...
<!-- region Forces the app to be executed when using mvn package -->
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>3.0.0</version>
<configuration>
<mainClass>${main.class}</mainClass>
</configuration>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>java</goal>
</goals>
</execution>
</executions>
</plugin>
<!-- endregion -->
...
</plugins>
</build>
This way when we execute goal package with: mvn package the plugin will be executed and the application runned.