How can I read/write jar files

I was interested in creating some jar packages from my program and being able to read from them. I was wondering does anyone know of a basic tutorial on how to do this. When I query jar files almost everything seems to tutorials on how to do this from the command prompt. Any help?

PS. Am I able to get the text in a text file contained in a jar files without fully extracting the package.

[402 byte] By [@GeneAnthonya] at [2007-11-27 1:35:17]