This is a simple modding/plugin system in Java. It is a proof of concept how it could be done.

This was originally created as a Demo for Home Grown - a Farming Game made by Thinmatrix.

Inside the game.modding folder you can see a few files. The ModLoader will load all mods that are inside the mods folder and create, instantiate and initialize them with a reference to the Game object. The GameMod is an interface that every mod has to implement.

Inside the Game class a new ModLoader is created and updated every game cycle.

To create a mod you have to create a new class that implements the GameMod interface. Inside the GameMod interface you can see a few methods that you have to implement.

public interface GameMod {
    void init(Game game);
    void update();
}

The init method is called when the mod is loaded and the update method is called every game cycle.

Since this project uses Maven it already comes with the correct configuration.

The Modders usually don't have access to the source code of the game, so they have to use the Game JAR itself as a dependency.

If they got the JAR they can modify the pom.xml file and change the systemPath of the dependency to the path of the JAR.

    <dependencies>
        <dependency>
            <groupId>me.lebogo</groupId>
            <artifactId>game</artifactId>
            <version>1.0-SNAPSHOT</version>
            <scope>system</scope>
            <!-- <systemPath>${project.basedir}/../game/target/game-1.0-SNAPSHOT.jar</systemPath> -->
            <systemPath>JAR PATH HERE</systemPath>
        </dependency>
    </dependencies>

Creating a Mod JAR is very simple. If you have Maven installed you can just run mvn clean package inside the mod folder and it will create a JAR inside the target folder.

This jar can be copied into the mods folder of the game and it will be loaded automatically.