I'm with you on disliking the software center. The only problem I ever have
with synaptic is it can be confusing to decide what to install when there
are so many options. For V9.04 of Ubuntu (on a VM which is all I have
access to at the moment) typing java into the synaptic search brings up a
slew of packages. It looks like the "sun-java6-bin" is the one to go with.
Selecting this package will also auto-select the plugin package needed for
browser support. Not sure if there is a more recent version in 10.04, but
it should be in the format of "sun-javaX-bin". OpenJDK runtime environment
seems to be another option that would work (maybe it is currently the
prefered option?). I've not had the need to test either as of yet...