Install the Sun Java6 JDK on Ubuntu 10.04.
The problem was that the system couldn’t find sun-java6-sdk and apt-get showed the message:
Package sun-java6-jdk is not available, but is referred to by another package.
To solve this problem you need to add a new source
sudo add-apt-repository "deb http://archive.canonical.com/ lucid partner"
After that run:
sudo apt-get update
sudo apt-get install sun-java6-jdk
sudo install