I'm trying to test JDK9 (jdk-9-ea+147 version) with Eclipse Oxygen IDE.
I've installed jdk along with jre. From Eclipse Market Place I've installed Java9 Beta extension:
The problem is, when I'm trying to add new installed jre from Eclipse I get following error:
Interesting thing is that this error doesn't occur with installations of previous JDK versions:
Does anyone encounter simillar problem with Eclipse Oxygen? Any feedback is appreciated.
I've just successfully tested JDK9 with Eclipse Oxygen IDE following the approach you detailed.
Here are the details of my installation (under Windows 10):
I downloaded and installed Java jdk-9+181 from http://jdk.java.net/9/
I downloaded and installed Eclipse Oxygen from https://www.eclipse.org/downloads/download.php?file=/oomph/epp/oxygen/R/eclipse-inst-win64.exe
I started Eclipse and attempted to add JRE9 (Windows -> Preferences -> Java -> Installed JREs -> Add...)
I got the error reported in the OP ("Target is not a JDK root...").
I then installed Java 9 Support (BETA) for Oxygen as detailed here: https://marketplace.eclipse.org/content/java-9-support-beta-oxygen
I restarted Eclipse and tried to add JRE 9 again. This time it worked fine: