So I installed the Java addon. But where is it?

Thanks for your reply Stefan. I really would like to get Java up and running so that I can attempt to install serviio.

Here's the result of the command you suggest:

MainStore:/# apt-get -y install sun-java5-jre
Reading package lists... Done
Building dependency tree... Done
The following extra packages will be installed:
  java-common sun-java5-bin
Suggested packages:
  equivs sun-java5-plugin ia32-sun-java5-plugin sun-java5-fonts ttf-baekmuk ttf-unfonts ttf-unfonts-core ttf-kochi-gothic ttf-sazanami-gothic ttf-kochi-mincho
  ttf-sazanami-mincho ttf-arphic-uming
Recommended packages:
  libasound2 libxext6 libxi6 libxp6 libxt6 libxtst6 gsfonts-x11
The following NEW packages will be installed:
  java-common sun-java5-bin sun-java5-jre
0 upgraded, 3 newly installed, 0 to remove and 32 not upgraded.
Need to get 30.0MB of archives.
After unpacking 83.1MB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
  java-common
E: There are problems and -y was used without --force-yes
MainStore:/# 

The thing I dont understand is that I installed it via frontview and it never barked. Just installed and said good to go. I dont see anythng in /var/log.

of course, on 4.2.19 I cant run apt-get update. What is the score with this anyway? When can we expect to be able to get it?