i dont know how to describe it but here is the code ive put in eclipse + the guide i used
https://codakid.com/guide-to-minecraft-modding-with-java/
[2021-06-12 22:53:07] [INFO ] Natives: C:\Users\amine\Desktop\mc gd hax\build\natives [2021-06-12 22:53:07] [INFO ] Main Class: net.minecraft.launchwrapper.Launch [2021-06-12 22:53:07] [INFO ] Srg2Mcp: C:\Users\amine\Desktop\mc gd hax\build\createSrgToMcp\output.srg [2021-06-12 22:53:07] [INFO ] Extra: [] [2021-06-12 22:53:07] [INFO ] Running with arguments: [--version, 1.12, --assetIndex, 1.12, --assetsDir, C:\Users\amine.gradle\caches\forge_gradle\assets, --accessToken, {REDACTED}, --userProperties, [], --tweakClass, net.minecraftforge.fml.common.launcher.FMLTweaker] Exception in thread "main" java.lang.reflect.InvocationTargetException at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:564) at net.minecraftforge.legacydev.Main.start(Main.java:86) at net.minecraftforge.legacydev.MainClient.main(MainClient.java:29) Caused by: java.lang.ClassCastException: class jdk.internal.loader.ClassLoaders$AppClassLoader cannot be cast to class java.net.URLClassLoader (jdk.internal.loader.ClassLoaders$AppClassLoader and java.net.URLClassLoader are in module java.base of loader 'bootstrap') at net.minecraft.launchwrapper.Launch.(Launch.java:34) at net.minecraft.launchwrapper.Launch.main(Launch.java:28) ... 6 more
