Some help creating a batch file please

I am currently working on a batch file, and i want it's function to copy .class files into a .jar file. How would I go about doing that?

Would I have to write the script to decompile the jar file into a folder, copy the .class files to that folder then recompile the .jar file?

Or is there a way I can tell my batch file to inject those class files straight into the jar file?

You can use the JAR program which is included with the JDK. Type jar at the command prompt
for details and examples.

Note: The JDK was put on your path when it was installed. Most likely is located: Java\JDK6\bin

Good luck. 

thx, now would i be able to distrubite the batch file even if the client doesn't have the JDK? or would I have to provide something in the folder with the batch file?