How do i edit a .class file and add it back into a .jar?

[karma]

Hey all,

I have a program in java that was made a while ago for me but my coder has gone awol. i need to be able to change a line in one of the .class files which is located within the .jar then i need to add it back into the .jar in order to run the program successfully.

I can extract the files using winrar and then edit the class file in notepad but a lot of the text is garbled. I have then tried creating an archive with the extension .jar instead of .rar but it wont work like that.

Does anybody know the best way to do this?

Thanks in advance

[The2]

DJ Java decompiler :) but you will encounter a lot of problems.. are you trying to crack a program? :ninja:

[karma]

no mate, its a simple line of code i need to change basically a url. ill try your suggestion

[The2]

I've never tried, but It should work if you decompile all clasess, because if you decompile only one, that one won't have other classes that are "imported" (ofcourse if depends on some other from the application)

[divinatum]

Jar files are zip files, rename to zip, extract, modify class, zip up, rename to .jar, should be good to go.

[karma]

hmm i have no idea whatsoever what i am doing with this program :s is there an easier program that will do it?

  divinatum said:

Jar files are zip files, rename to zip, extract, modify class, zip up, rename to .jar, should be good to go.

Hi and thanks for your reply. what should i edit the class with?

[monkey13]

Never used this myself but you could give Class Editor a go.

[karma]

Thanks monkey i was able to edit the class file with that program but now i am having troubles creating the .jar.

I am using winrar to create the archive and simply giving the extension of .jar but when i try to run it with cmd i get corrupt archive message

[monkey13]

You could try feeding the edited class file back into a copy of the original with the Jar toolbox (in the JDK).

jar uf jar-file input-file(s)

[JamesCherrill]

Yiu should be able to open the jar with your favourite zip file utlility, and simply replace the file with your new version. As long as the name is the same, you shouldn't have to change anything else.

[karma]

Thanks for the help guys. all working now.

I managed to get it .jared up using http://www.figmenttech.com/jc/index.html

Thanks again