pi@raspberrypi:/opt/openhab $ sudo apt-get purge openjdk-7-jre
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
  default-jre* openjdk-7-jre*
0 upgraded, 0 newly installed, 2 to remove and 39 not upgraded.
After this operation, 431 kB disk space will be freed.
Do you want to continue? [Y/n] y
(Reading database ... 142830 files and directories currently installed.)
Removing default-jre (2:1.7-52) ...
Removing openjdk-7-jre:armhf (7u95-2.6.4-1~deb8u1+rpi1) ...
update-alternatives: using /usr/lib/jvm/jdk-8-oracle-arm32-vfp-hflt/jre/bin/policytool to provide /usr/bin/policytool (policytool) in auto mode
Processing triggers for hicolor-icon-theme (0.13-1) ...
Processing triggers for gnome-menus (3.13.3-6) ...
Processing triggers for desktop-file-utils (0.22-1) ...
Processing triggers for mime-support (3.58) ...
pi@raspberrypi:/opt/openhab $ java -version
java version "1.7.0_95"
OpenJDK Runtime Environment (IcedTea 2.6.4) (7u95-2.6.4-1~deb8u1+rpi1)
OpenJDK Zero VM (build 24.95-b01, mixed mode)