I installed Ubuntu a few days ago and found that my client, Azureus, which had been performing well thus far on Windows (the previous OS on that box), was, all of a sudden, no longer connectable or providing extremely slow speeds. I tried playing with firewalls and what not, but finally came across the answer when I tried downloading a torrent from OiNK. The torrent failed with an error stating that my version of Java was incompatible with the version of Azureus (2.5) that I was running.
Therefore, I then proceeded to investigate how I would update Java on Ubuntu. I had a quick check in Synaptic (which is Ubuntu's package manager), and sure enough, I did have an option to install Sun's Java 5 (JRE 1.5.0). A couple of clicks and a quick download later, I was told that Java 5 was installed on my system.
I happily restarted Azureus in the hope that my problems would now be at an end.. but alas, this was not to be. There was no improvement whatsoever. I decided to check which version of Java was actually installed on my box, using:
and to my surprise, I was told that my box was still running 1.4.2 instead of 1.5.0. A quick google informed me that I could have multiple versions of java running on my system and that I could set the default version using the following syntax:
sudo update-alternatives --config java
and sure enough, I was presented with an option to change the default version of Java. I selected 1.5.0 and restarted Azureus once again, ensuring that my fingers, toes and any other appendages were crossed (ouch!). Voila! Speeds were back to normal, the OiNK torrents were no longer complaining and my heart, mind and soul were at ease once again.
End of story.