At the time this was written, Sun's latest JDK can be found here. Assuming you want an RPM-based install, what you will end up downloading is an executable binary that, when run, will produce the RPM you want:
# bash j2sdk-1_4_1_01-linux-i586-rpm.binwhich produces the RPM file j2sdk-1_4_1_01-fcs-linux-i586-rpm.
Once you extract the RPM file, just install it with:
# rpm -ivh j2sdl-1_4_1_01-fcs-linux-i586.rpm
You can download the binary file and extract the RPM file in any directory you want, even as a normal user. But each of them is just over 40M in size, so make sure you have the room.
You do, of course, have to be root to install the RPM.