What is the difference between "Update snapshots" and "Update dependencies" in m2eclipse?

Question

Assuming you're already using the m2eclipse plugin, if you right-click on a Maven project there is a Maven submenu.

Two of the actions available in this submenu are:

• Update dependencies
• Update snapshots

I've found an answer that says that "Update snapshots" is equivalent to using the -U parameter for mvn.

If "update snapshots" is the same as mvn -U what does "update dependencies" do?

Answer 1

Snapshots are dependencies, but used slightly differently. Specific dependency is determined using group, name and version. These attributes can be identical for two different snapshots. Maven uses the latest snapshot based on internal time stamp.

Shapshots are beneficial during development of the project where you don't want to change its version but want your users to use the latest build.

So... "update dependencies" downloads dependencies you don't have, leaving the ones you have intact, "update snapshots" updates your snapshots in place to the latest build.

I hope this helps.

Answer 2

It largely depends on how snapshot updating policy is set in your environment. By default Maven is supposed to update snapshots once a day (hence the flag -U and "Update Snapshots" action to force the snapshot update), but this policy can be overwritten locally or at repository manager level.

The "Update Dependencies" does pretty much the same as "Update Snapshots" action, except forcing updating snapshot artifacts. Both actions reset in-memory project model created by M2E to keep track of dependencies, including those that came from Eclipse Workspace.