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From Petter Måhlén (JIRA) <>
Subject [jira] Commented: (MDEP-275) Figuring out duplicate class definitions using the Analyze goal
Date Fri, 06 Aug 2010 07:17:32 GMT


Petter Måhlén commented on MDEP-275:

By the way, to make it easier for other people who are interested in using this feature, I
have created a couple of repositories with the code. The repositories are:

For instructions on how to start using it, see

> Figuring out duplicate class definitions using the Analyze goal
> ---------------------------------------------------------------
>                 Key: MDEP-275
>                 URL:
>             Project: Maven 2.x Dependency Plugin
>          Issue Type: Improvement
>          Components: analyze
>    Affects Versions: 2.1
>            Reporter: Petter Måhlén
>            Assignee: Brian Fox
>         Attachments: dependency-analyzer.diff, dependency-plugin.diff
> Hi,
> I've pretty frequently run into issues where changes to the library structure of some
product (that is, changing the way that classes are grouped into libraries) leads to the same
classes being defined in more than one place. This can lead to system-dependent problems,
because different versions of the same class are being loaded by different systems.
> I was going to create a new goal for the dependency plugin to check for duplicate classes,
but when I looked a bit closer at the analyze goal, it already had all the information needed
to do that check as well, so I came up with some changes that add this functionality.
> The intended usage is something like:
> mvn dependency:analyze -DcheckDuplicateClasses
> I get the feeling that I might want to add the ability to exclude certain packages (that
I might be comfortable are safe to have duplicates of), so I added this option too:
> mvn dependency:analyze -DcheckDuplicateClasses -DexcludePrefixes="org., net.sf.cglib,
javax.xml, junit."
> The output looks something like:
> [WARNING] Duplicate class definitions found:
> [WARNING] defined in: 
> [WARNING] defined in: 
> [WARNING]       com.shopzilla.site2.sasClient:sas-client-core:jar:5.47:compile
> [WARNING]       com.shopzilla.site2.service:common-web:jar:5.50:compile
> A couple of notes:
> - I was unable to get configuration (setting checkDuplicateClasses, etc.) using the pom
to work, but I think that might be due to lack of understanding on my part.
> - I don't fully understand the effect of calling compileProject() during unit tests,
but I think it may be sufficient to call it only once for the duplicateClasses project, during
setUp(). That would speed up the unit tests.
> - I haven't added duplicate class definition checking to the AnalyzeReportMojo, because
I wanted to get some feedback on whether this addition was felt to be valuable before spending
any time on that.
> - A lot of the unit test dummy code in the attached diff files needs cleaning up, but
again I wanted to wait with that until hearing whether this might be useful to others.
> - I made an API change in the ProjectDependencyAnalyzer interface, which might be an
issue if there are other implementations than the default one. That change was only needed
to support the 'exclude package' feature, which might not be super-important.
> Cheers,
> Petter

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