maven versions release candidates and snapshot

Question

My goal is to release a project which have a single dependency. I have a nexus repository where i deploy both snapshot and release versions.

The one dependency I have has

group:artifact:1.1.0-SNAPSHOT

and the following Release Candidate is released in my nexus repo

group:artifact:1.1.0-RC1

when asking to the versions plugin to resolve the dependencies, it claims that no new dependency is available. So he consider that

1.1.0-SNAPSHOT > 1.1.0-RC1

However, If in my project, i have version 1.0.0-SNAPSHOT, version 1.1.0-RC1 is resolved as the newest version.

What am I missing? (I looked into the plugin sources and we have the following snippet:

String otherQualifier = otherVersion.getQualifier();

if ( otherQualifier != null )
{
  if ( ( qualifier.length() > otherQualifier.length() )
      && qualifier.startsWith( otherQualifier ) )
  {
    // here, the longer one that otherwise match is considered older
    result = -1;
  }
  else if ( ( qualifier.length() < otherQualifier.length() )
      && otherQualifier.startsWith( qualifier ) )
  {
    // here, the longer one that otherwise match is considered older
    result = 1;
  }
  else
  {
    result = qualifier.compareTo( otherQualifier );
  }
}

which seems buggy to me. Any idea?

Solution

Maven version numbers are comprised as follows:

<major version>.<minor version>.<incremental version>-<qualifier>

If all the version numbers are equal, the qualifier is compared alphabetically. "RC1" and "SNAPSHOT" and sorted no differently to "a" and "b". As a result, "SNAPSHOT" is considered newer because it is greater alphabetically. See this page as a reference.

Note that a.b.c-RC1-SNAPSHOT would be considered older than a.b.c-RC1.

I'm not sure what to suggest as a solution - this is just how Maven versioning works.

Comments

[Angel O'Sphere]

This is only half correct, as SNAPSHOT is a special qualifier which is handled by maven outside of the process you are describing. See: docs.oracle.com/middleware/1212/core/MAVEN/…

[jmrah]

This answer might have been correct at the time of writing, but the way Maven compares versions has been updated since around v3. More details here stackoverflow.com/questions/13004443/…