9

I'm writing a Maven plugin and I am using default values for all parameters such as this:

/**
 * The file with the site structure.
 * 
 * @parameter expression="${generateSite.siteFile}" default-value="${basedir}/src/oda/site.xml"
 */
private File siteFile;

Now I am adding a new parameter which is a collection. Is there a way to set default values for a parameter like the following one?

/**
 * A list of file/directory names to exclude in the processing.
 * 
 * @parameter ????
 */
private Set<String> excludes;
Pascal Thivent
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Peter Becker
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2 Answers2

8

To my knowledge, this is actually not possible, there is no real way to specify default values for Parameter Types With Multiple Values (like Arrays, Collections, or Maps), at least not as parameter. I had to do this in the past too and, having read threads like array (or collecton) as a default-value of a mojo configuration parameter or configuring a list as default value for a plugin parameter, I ended up setting defaults in the execute() method, like Chris mentioned in a comment to his answer (see for example the flexmojos:wrapper plugin sources and the parameters parameter).

Community
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Pascal Thivent
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  • That's the answer I suspected I would get. I had a brief glimpse at the Maven source code, but then it seemed I needed the Plexus source, too -- which is where I stopped. Let's just assume you are right ;-) – Peter Becker Nov 03 '09 at 00:13
  • Well, I'm still not 100% sure but flexmojos being developed by Sonatype, I guess they are representative of state of the art and are a trustful reference. – Pascal Thivent Nov 03 '09 at 00:47
-1

I don't think that Set is explicitly supported but the following will work:

/**
 * A list of file/directory names to exclude in the processing.
 *
 * @parameter
 */
private String[] myFiles;

You can then configure it using: 

<myFiles>
  <param>value1</param>
  <param>value2</param>
</myFiles>

BTW this was taken from the Parameter Types With Multiple Values section on this page which also details other ways to allow parameters with multiple values.

Chris
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  • According to the documentation you link to yourself any java.util.Collection should work -- this is how I came up with the original plan. It definitely does work with a Set in the way you describe it. But that is not setting default values, it is the normal project-specific configuration. The documentation does not mention anything about setting default values on the multi-valued parameters (or not being able to). – Peter Becker Nov 02 '09 at 04:06
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    Sorry, I obviously didn't read the question properly! However, I believe the answer is no. A few years ago I was seeking a similar answer on the Maven mailing lists, and I only found "I don't think so" answers. Digging around the Plexus code (which Maven uses a container) and this supported that answer. In the places that we wanted to do this, we ended up just setting the defaults in the execute() method. – Chris Nov 02 '09 at 06:27