I just wonder when developing a big java project we always use a svn repository for code sharing but is it possible to run the project in that repository?
Or is there any system for java that allows more than one user to develop and test same project in one place?
The repository only stores your code you cannot run the code from the repository.
If you want to build/test the code centrally then you need a Continuous Integration Server (CI) like Jenkins (http://jenkins-ci.org/)
This server can extract the project from svn build it, run the tests (if any) and even deploy it on a server.