Summary

Have javac recognize "9" as a valid argument for the -source and -target options.

Problem

New JDK release, new source and target values are needed in javac.

Solution

Add javac options -source 9 -source 1.9 -target 9 -target 1.9

Specification

-source 1.9
The compiler accepts code with features introduced in Java SE 9.
 
-source 9
Synonym for 1.9.
 
-target 1.9
The compiler outputs class files appropriate for the 9 platform.
 
-target 9
Synonym for 1.9.