EDIT: According to this answer since Eclipse Oxygen (4.7.0) you can use a run configuration of the type Launch Group for that.
Just install “C/C++ Development Tools” from the CDT (see eclipse.org/cdt/downloads.php ) – this single package is enough, no other CDT packages are needed. This won’t disturb your Java environment 😉 Then you have “Launch Groups”, for any kind of project, including Java projects. See the following screenshot:
You can run or debug the projects (also mixed mode), define delay times and so on. Have fun!