Basic Code Structure

In this article I will be explaining the basic structure of your mod’s code.

Directory structure

As you may or may not know all your code should reside in the src/main/java/ directory and under that directory you should have a structure matching the group from your build.gradle as explained in the first tutorial

Main Class

This is probably the most important class in your mod. While it often doesn’t contain much code it is the main entry point of your mod.

package com.example.examplemod;

import net.minecraftforge.eventbus.api.IEventBus;
import net.minecraftforge.fml.common.Mod;
import net.minecraftforge.fml.event.lifecycle.FMLClientSetupEvent;
import net.minecraftforge.fml.event.lifecycle.FMLCommonSetupEvent;
import net.minecraftforge.fml.javafmlmod.FMLJavaModLoadingContext;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import static com.example.examplemod.ExampleMod.MODID;

@Mod(MODID)
public class ExampleMod {

    public static final Logger LOGGER = LogManager.getLogger();

    public static final String MODID = "examplemod";

    public ExampleMod() {
        IEventBus bus = FMLJavaModLoadingContext.get().getModEventBus();

        bus.addListener(this::setup);
        bus.addListener(this::clientSetup);
    }

    private void setup(final FMLCommonSetupEvent e) {
    }

    private void clientSetup(final FMLClientSetupEvent e) {
    }

}

As you can see for the basic set up you don’t need much.

@Mod

Let’s start with the @Mod annotation. All you need in here is your modid.

It lets forge know that this class is the entry point of your mod.

LOGGER

The logger is used to log information useful for debugging, resolving conflicts with other mods or just additional info for when a user reports an issue.

Constructor

This is what forge uses to get an instance of your main class. In here you can register listeners for various lifecycle events of your mod like FMLCommonSetupEvent, FMLClientSetupEvent and so on.

FMLCommonSetupEvent

This event (and thus the #setup function) can be used to perform any setup required on both sides. Most of the time it will be empty because you can just use other more specific events for most things.

FMLClientSetupEvent

Same as FMLCommonSetupEvent but fires only on the client side.