This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
One note, although compiling a jar and building it are usually done together, they are not exclusive to one another. You take a bunch of files that have all ready been compiled, add create a jar out of them. Really, a jar is the java equivalent of a zip file that can hold any type of file, compiled or not.