Main Class

package iitest;

import iitest.capability.ITest;
import iitest.capability.ITestImpl;
import iitest.capability.ITestStorage;
import iitest.gui.TestHandler;
import iitest.item.ItemTest;
import net.minecraftforge.common.capabilities.CapabilityManager;
import net.minecraftforge.fml.common.Mod;
import net.minecraftforge.fml.common.event.FMLInitializationEvent;
import net.minecraftforge.fml.common.event.FMLPreInitializationEvent;
import net.minecraftforge.fml.common.network.NetworkRegistry;
import net.minecraftforge.fml.common.registry.GameRegistry;

@Mod(modid = "iitest", name = "IInventory Test", version = "test")
public class IITest {
    @Mod.Instance("iitest")
    public static IITest instance;

    ItemTest item = new ItemTest();

    @Mod.EventHandler
    public void preinit(FMLPreInitializationEvent event) {
        CapabilityManager.INSTANCE.register(ITest.class, new ITestStorage(), ITestImpl.class);

        item.setRegistryName("iitest", "item");
        item.setUnlocalizedName(item.getRegistryName().toString());
        GameRegistry.register(item);
    }

    @Mod.EventHandler
    public void init(FMLInitializationEvent event) {
        NetworkRegistry.INSTANCE.registerGuiHandler(instance, new TestHandler());
    }
}