Does Grails 3.x support Java 11

Well I know that the support for Java 9+ in Groovy is getting worked on and I think 2.5.2 had some fixes. Technically Groovy will work on newer versions of java, but you'll get a bunch of warnings. All of this is supposed to be worked out for Groovy 3.0, probably coming around the end of the year, based on what I hear at GR8Con.US.

All that being said, Grails 3.3 is on Groovy 2.4.x, with spring boot 1.2, which I don't think either support newer versions of Java. Grails 4 is supposed to be coming out by the end of the year, with Groovy 2.5, and a newer version of spring boot. Once Groovy 3 comes out it shouldn't be too long before Grails upgrades to it.

Also check out the Groovy Podcast, there was a metion on the support from Groovy: https://youtu.be/XQLblr2OGJ8

I know Java 11 has not been officially released yet, but has anyone tested Grails 3.x with an early access release of Java 11?

I tried using Grails 3.3.8 and the early access release of JDK 11 and it didn't work, but I wondered if that might be something to do with the JDK.

Then I tried again using Oracle's official release of JDK 11 which came out a couple of days ago. I rebuilt an existing Grails project in NetBeans 9.0 using JDK 11 / Grails 3.3.8, and got the following error:

Command [clean] error: Could not determine java version from '11'. (Use --stacktrace to see the full trace)

I get similar errors when using JDK 9 and 10, but the project builds and runs fine using JDK 8.

See this SO answer for a similar problem when using Grails with JDK 10: Could not determine java version from '10.0.2' while starting Grails 3.3.8 application:

Grails 3.3.8 does not support Java 10. You will have to use Java 7 or Java 8 if you want to use Grails 3.3.8.

Or does anyone know when or if Grails 3.x will support Java 11?

Grails 3.x won't ever support JDK 11 according to a Grails developer. See the comments for the SO answer I linked to above:

You have to wait for Grails 4 to use a JDK > 8.

I don't know anything about a proposed release date for Grails 4.