how to edit source code in JAR file and combine it again?

I have extract the JAR file with winrar, and i able to saw all the class file which inside the JAR file.

I wish to edit some of the source code for the entire JAR file, and combine it again become a new JAR file which can work properly. I have successful to edit the source code in class file, how can i combine it again??

is it i need to create a new project? copy all the source code in class file to a java file? i have no idea and i am still new to this. thanks if got any comment o开发者_如何学编程r better solution.

Google is your Freind : "Java create a jar"

http://download.oracle.com/javase/tutorial/deployment/jar/build.html