Looking to try out OpenJDK 9? If you didn’t know, OpenJDK 9 is going to be the reference implemtation for Java 9 (assuming the pattern for Java 7 and Java 8 continues). Pre-release packages for Fedora 23, 24, 25 and Rawhide as well as RHEL 7 are available on copr:
Please note that these are not official Fedora (or RHEL) packages. Official Fedora packages will be proposed and added to Fedora closer to OpenJDK 9’s release.
To install on Fedora:
# dnf copr enable omajid/openjdk9 # dnf install java-9-openjdk-devel
To install on RHEL (or CentOS) 7:
$ wget https://copr.fedorainfracloud.org/coprs/omajid/openjdk9/repo/epel-7/omajid-openjdk9-epel-7.repo $ su - # cp omajid-openjdk9-epel-7.repo /etc/yum.repos.d/ # yum install java-9-openjdk-devel
Then use as follows:
$ /usr/lib/jvm/java-1.9.0-openjdk/bin/java -version
To make it the default Java version, use update-alternatives.
# update-alternatives --config java # update-alternatives --config javac
If you are a user, making 9 the default may not be a great idea – OpenJDK 9 is in heavy development and lots of things are changing. There are also some known compatibility issues. On the other hand, if you are a Java developer, this will give you a good idea of how prepared your favourite libraries and tools are for Java 9.