Java 9 options --add-exports vs. -XaddExports not recognized

Question

I downloaded the latest jdk9 build:

java version "9-ea"
Java(TM) SE Runtime Environment (build 9-ea+142)
Java HotSpot(TM) Server VM (build 9-ea+142, mixed mode)

When I execute

/path/jdk-9/bin/java -X

I see the option:

--add-exports <module>/<package>=<target-module>(,<target-module>)*
                  updates <module> to export <package> to <target-module>,
                  regardless of module declaration.
                  <target-module> can be ALL-UNNAMED to export to all
                  unnamed modules.

But when I try to use this option:

/path/jdk-9/bin/java --add-exports:java.base/jdk.internal.ref=ALL-UNNAMED -jar some.jar 

I get:

Unrecognized option: --add-exports:java.base/jdk.internal.ref=ALL-UNNAMED

The same for -XaddExports which I saw in some posts.

What am I doing wrong here?

Do I need a special jigsaw jdk9 distribution? I'm a bit confused about the different jdk9 versions to be honest ;)

Answer 1

The two flags have slightly different syntax. At some point (I think it was build 9-ea+113) where the JVM switched over from -XaddExports to the --add-exports syntax, as part of the effort for JEP 293 which aims to achieve GNU-style syntax for command line arguments.

Current syntax:

--add-exports <module>/<module>/<package>=<target-module>(,<target-module>)*
--add-reads <module>=<target-module>(,<target-module>)*

Note: Some utilities may have trouble accepting the new --key value style of arguments because there is a space between them, in that case you can put also put an equals sign in the middle (i.e. --key=value) to satisfy those utilities.

Old syntax:

-XaddExports:<module>/<module>/<package>=<target-module>(,<target-module>)*
-XaddReads:<module>=<target-module>(,<target-module>)*

Unfortunately, it's very easy to miss the space to colon change. I've messed it up several times myself.