Help Edit jar files

[barao45]

Hi Friends. I am learning a little how to edit jar files from the Core, i Need to modify the engine.jar to add some lines in donatemanager class for the classes changer but i got an error when i import the jar file to my proyecto,for example error in imports Like log4j.

Could you explain the Steps to modify and import this files to our project?.

[Rootware]

If you need change any class from JAR package then you need:

 

• Decompile the target class;
• Create new Java project in IDE as container of target class (project can includes only "dead code");
• Normalize all fields and methods;
• Restore all imports with external dependencies;
• Compile as new project;
• Replace new class from new JAR package to old.

For all you need any IDE (Eclipse, IntelliJ IDEA) and any Jva decompile (e.g. Java Decompiler)

[barao45]

11 hours ago, Rootware said:

If you need change any class from JAR package then you need:

 

• Decompile the target class;
• Create new Java project in IDE as container of target class (project can includes only "dead code");
• Normalize all fields and methods;
• Restore all imports with external dependencies;
• Compile as new project;
• Replace new class from new JAR package to old.

For all you need any IDE (Eclipse, IntelliJ IDEA) and any Jva decompile (e.g. Java Decompiler)

 

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Thanks Root, i have exported source from engine.jar, i have created a Java Project with java 11 because Sunrise use that. then i copy the files to the project and imported a library of l24j. That error has been resolved, but tha source has an error because cant find de l2r.DatabaseFactory and L2PCInstance. i share the images.

If i export that source i think that it wouldnt work.

 

https://ibb.co/z28XxKg

https://ibb.co/TvZbYf8

[Rootware]

You need restore all dependencies. It means you need:

 

• reproduce classes irerarchy and package location (e.g. if target class locates by path "l2j.net.sf.gameserver" you need create this package path in your new project and put there target class);
• if target class calls some methods from classes from this package then you need create this classes as DUMMIES and reproduce them empty methods/fields for exclude logical errors while compilation. This names as "make a dead code";
• compile result and take modified class for replacing.

That's all steps i meant by phrase "Restore all imports with external dependencies".

 

Sometimes recompilation the target class requeres a lot of time and new project can includes few hundreds "depended" classes. You must be ready for this.