Technical details for https://stackoverflow.com/a/44169445/6730571
On a base system, /usr/bin/java is a symlink that points to /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/java, which is an Apple wrapper tool that locates and executes the actual java.
(Do not touch anything in those 2 system directories. It should actually be impossible due to "System Integrity Protection" anyway.)
If you don't have Java installed, attempting to execute java will open a dialog that invites you to install it.
