To view / edit Java source files from Netbeans:
- Create a new Project
- Right-click on the project and view its Properties
- In the left-hand list click the category: sources
- Click the right-hand button: Add Folder
- 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.