It seems that there are things that the Open Source community can’t provide. One of those is the java virtual machine and the corresponding java sdk. Although under Ubuntu the default option is the gcj, one of the first thing I do is replacing it with a better one. There are two competitor (or is it just one, after all Oracle bought Sun Microsystems) : the Sun’s JAVA VM and Oracle’s JRockit JVM.
After installing one or both VM, one can simply switch between them using:
sudo update-alternatives --config java sudo update-alternatives --config javac sudo update-alternatives --config jar