What are the possible metrics by which I can assess whether a Java library is suitable to use?

Issue

Before starting on a new Java Open Source Framework (e.g. ProjectReactor) or a including a new Open Source Library (e.g. Jackson), I would like to know how popular and stable these dependencies are. In particular I would like to know how many times have these been downloaded. With many maven repositories (Nexus, Artifactory) in play, is there a way to get this information? E.g. if I go to maven central and search for these dependencies, I don't see #downloads?

With JavaScript libraries, this is so much easier. All I need is to go to https://www.npmjs.com and search for the package. It shows the #downloads right there.

If there is no easy way to get #downloads, what are the possible metrics by which I can assess whether a Java library is suitable to use?

Edit:
Some people suggested to use "Usages" in the maven central. But that is the count of how many times this dependency has been used by other maven projects in the maven central. IMHO that doesn't always give a good indication about how many times that library was used in enterprise or other non-open-source projects. Why does maven central not expose #download for everyone? Or maybe there is a way to get this information that I don't know of.

Solution

mvnrepository.com has the number of usages by other projects.

e.g. for Hamcrest

Used By 7,059 artifacts

Careful, this website isn't affiliated with Apache. I'm not sure how they get those stats but they probably build the graph themselves.

This blog post states that individual project owners can see download statistics, but I would infer from that that it's not public information. The post is 12 years old though so it may have changed since then.

Of course, there's always number of GitHub stars, which is a metric that's applicable for any language.

Answered By - Michael