Here i will show you how to use source codes for L2J OFF files!
You will need:I recommend this:
CLICKJRE:
CLICKJDK:
CLICKStep :: 1We install Eclipse and make a work folder named -> workspace
If you dont want the program to ask you more for your work place mark the box below
Step :: 2A new window (tab) will open, click X. Now we go in Window -> Preferences... and open the Java control.


after you do that click Add... After we click Browse... and find our JDK and press OK (default: C:\Program Files\Java\jdk1.6.0_10)
Step :: 3Now go to Help -> Software Updates -> Find and Install. Select "Search for new features to install" and press OK.
Now press "New Remonte Site" (in the left) and now write this:
Name : Subclipse
URL : http://subclipse.tigris.org/update
Select only Subeclipse!!! Demarc the other ticks!
It will update and after it will ask you to restart. do it
Step :: 4After you restarted it we go to Window -> Show View -> Other

after a new window appeared we select: SVN -> SVN Repository -> OK

Now you click the right mouse button on the new window and after New -> Repository Location...

A new window will appear for writing a link and we write:
http://www.l2jserver.com/svn/ - GameServer Source codes
http://www.l2jdp.com/svn/ - DataPack Source codesDONT WRITE BOTH ON ONE TIME! first the one, and after the other!
After loading finishes a new directory will appear in the Repository tab.
Duble click on it and a new folder called trunk will appear.
Duble click on the folder trunk and now must appear the folder L2_GameServer. Right click on it and click Checkout.
Select "Check out as project in the workspace" and for name you write L2_GameServer , after Finish.
Now it starts to download source codes (it can take a long of time... it depends on your internet connection and their server).
If you have added the 2nd link repeat it but with the name L2_Datapack.
Step :: 5After eclipse had restarted itself we go to Window -> Show View -> Ant

and now we add build files from the downloaded sources .
Right click and Add Buildfiles.
2 folders will appear named L2_GameServer / L2_Datapack (if you arent renamed it)
Credit: pa40