So first step is to install java:
apt-get install openjdk-9-jdk openjdk-9-demo openjdk-9-doc openjdk-9-jre-headless openjdk-9-sourceThis just works like expected. But after that i installed eclipse.
Download via www.eclipse.org was easy and the installation ran without any error.
But Eclipse was not able to find the JRE for compiling, autocorrection, etc.
For all developers, which are not used to linux:
The JRE is in Ubuntu located here:
/usr/lib/jvm/java-9-openjdk-amd64/jreAnd it is added like on any other platform via the preferences window: