[OT] how to make a folder be a jar file

[Colin Holgate]

I have a need to edit a single character in a class file inside a jar file. My steps are:

rename the file to .zip
expand it
use a hex editor to make the single character change
compress the folder
rename back to jar

The jar file I get is seen to be bad. If I leave out the class editing, and just rename, decompress, compress, rename, that’s enough for the jar to not work.

Anyone have some insights as to how to expand and archive a jar file, without breaking it?