Modifing a single file in a game application

I would like to improve the Artificial Intelligence of a "Risk/Domination" game developed in Java (Domination). The source code is available to download.

Looking at the source code of the AI I can manage to understand 80% of the java language and of the scope of each class in the AI file. My issue is not therefore on java language but more on "playing with jar files and compiled java files"

The structure of the source files (provided in src.zip format) is the following (AIHard.java is the file I would like to modify):
http://www.dydo-ai.kilu.de/files/src.jpg

The question is, once changed AIHard.java file, how can I re-compile the whole package and re-create the jar file to run the game? I know I have to compile the sources first and then to create the jar package. I managed to compile the famous HelloWorld.java (therefore I installed already JDK) but I have no idea what to do in this situation where multiple java files compose the game/application.

Thanks in advance!

woud this game have its own build mechanism already ? Many projects use "Ant" or "Maven" to do the work of automating the compiler and jar file building operations. So I would see what this project is happening to do already, it could be as easy as just invoking their existing "build the application" targets in their what ever they use build system.

Failing that, depending on the runtime deployment and folder paths, some Java applications have a batch file or a shell script to launch the java process. These either already have, or can be modified to, have several folders and jar files in the class path, so it should be possible to create a folder called "classes", and dump in the your single compiled .class file in the proper package folder into this classes folder, where your classes folder is higher up on the classpath than the jar files.

For example:

Code:

---

set CLASSPATH=./classes;./lib/jarfile1.jar;./lib/jarfile2.jar

---

Where any class found in the classes folder will be discovered first and 'override' the classes that live in the jar files. This approach is handy if you wanted to keep a clear separation between the original jar files of the software and the ones you created to customize some stuff.

Did you try to re-compile them? Just forget about the jar at the moment. If you can compile the file properly then you've done the modification correctly.

Then as travishein explain above, you've to check that the package comes with it's own build mechanism. Check weather it use any additional packages and how it connected at the moment. Based on that you can build the jar package if you want.

thanks, yes you are right! The game uses Ant, also I managed now to get in touch with the game developer which is now helping me out a bit...So now I need to learn also to use Ant...wow, I thought it would have been easier but I am not giving up! thanks again for the support.

So you can start from here.

Apache Ant - Welcome