[Error] Package sun-java6-jdk is not available, but is referred to by another package.

Ubuntu 11.10 (Oreinic)

If this error happens, just follow this.

$ sudo add-apt-repository "deb http://archive.canonical.com/ lucid partner"

# note that we use lucid repo, although we use oreinic, it works for me anyway

then

$ sudo apt-get update

$ sudo apt-get install sun-java6-jdk