I upgraded to Ubuntu gnome 14.10 this weekend. I've been curious to try out JavaFX, and noticed that there is now an openjfx package available. So I apt-get installed openjdk-8-jdk and openjfx and tried it out. Everything seemed to work fine, and I decided I didn't need another openjdk any longer. So I apt-get removed openjdk-7-jdk. When checking update-alternatives --config java, I noticed I now suddenly have three jdk's installed:
Selection Path Priority Status
------------------------------------------------------------
0 /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java 1071 auto mode
1 /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java 1061 manual mode
2 /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java 1071 manual mode
* 3 /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java 1069 manual mode
I'm not sure if I can run into problems if I have three different JDK's installed (except for the fact that it uses space on a not-so-large SSD), or if removing them can result in unexpected issues. I would like to remove two of them, but should I? And how can I? I found this answer, but I don't want to uninstall everything, just the jdk 6 and 7. Or is it best to just uninstall everything, and reinstall jdk 8 afterwards?