Ref. JEP 12 - Preview Language and VM Features

David Holmes david.holmes at
Wed Mar 7 01:00:29 UTC 2018

The JEP defines a "launcher flag" --enable-preview but it is unclear 
whether this is truly a launcher flag or a VM flag? Is the VM expected 
to process the --enable-preview flag and accept it via the JNI 
invocation API? Or does the launcher translate --enable-preview into a 
suitable -XX VM flag?

If the above is considered too implementation oriented for the JEP then 
at a minimum the JEP needs to clarify whether you can enable preview 
features via the JNI invocation API.


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