To view / edit Java source files from Eclipse:
- Create a new Java Project
- Untick "Use default location"
- Browse to the jdk/ folder, which contains the src, make and test folders. For example /home/openjdk/dev/jdk9/jdk on a Ubuntu VM, or smb://server/user/dev/jdk9/jdk if you are using a share from VM into the host machine. Press OK and be patient.
- Alternatively choose a sub-folder of the above, such as java.base/share/classes to work with a smaller sub-set.
Un-tick Eclipse's Build automatically setting to prevent build errors.