I am making a Java application that uses Git. I found that there is something called JavaGit, EGit and JGit.
I know that JavaGit and EGit/JGit are different. What I
JGit is git implemented from scratch as a Java library whereas JavaGit is (was ?) a Java API wrapping the native git implementation (i.e. it's calling the native git command line).
EGit is the Git Eclipse Team Provider integrating JGit into the Eclipse IDE and is providing the UI to work with Git from inside Eclipse.
In the meantime a large part of the Eclipse community and also a large number of corporate developers is using EGit/JGit (that's the reason why the companies backing these projects put money into that). See the project pages and ohloh if you want to get some insight who is contributing.