Creating Your Main Plugin Class

Tip

Using a common build system like Maven or Gradle? We might just have an existing template for you. Check Plugin Templates to see!

Note

The instructions within the Sponge Documentation assume that you have prior knowledge of Java. The Sponge API provides the foundation for you to begin creating plugins for Minecraft servers powered by Sponge; however, it is up to you to be creative and make your code work! There are several free Java courses online if you have had little experience with Java.

Starting Your Class

The next step after adding the Sponge API as a dependency is creating a new class. The class can be named however you’d like, and can be in any package that does not begin with org.spongepowered. By convention, class names should be in title case.

Oracle recommends to use your domain as your package name, if you own a domain. However, in the event that you do not own a domain, a common practice is to use an email address (such as com.gmail.username.project) or an open-source repository (such as io.github.username.project).

After creating your main class, the @Plugin annotation must be affixed to it. This annotation allows Sponge to easily find your main plugin class when your plugin is loaded. An example usage is illustrated below.

package io.github.username.project;

import org.spongepowered.api.plugin.Plugin;

@Plugin(id = "example", name = "Example Project", version = "1.0")
public class ExampleProject {
    // Woot! This is a comment!
}

Remember to change the ID, name, and version of your plugin in the annotation. The ID should be a simple identifier with no special characters or spaces, as it is used for generating configuration files and for identification purposes. That in mind, it is not recommended to change the ID after releasing the plugin.

Initializing Your Plugin

Plugins are loaded before the game and the world. This leaves a specific timeframe when your plugin should begin interacting with the game, such as registering commands or events.

Your plugin can listen for particular events, called state events, to be notified about changes in the state of the game. In the example below, onServerStart() is called when the GameStartedServerEvent occurs; take note of the @Listener annotation before the method.

import org.spongepowered.api.event.Listener;
import org.spongepowered.api.event.game.state.GameStartedServerEvent;
import org.spongepowered.api.plugin.Plugin;

@Plugin(id = "example", name = "Example Project", version = "1.0")
public class ExampleProject {
    @Listener
    public void onServerStart(GameStartedServerEvent event) {
        // Hey! The server has started!
        // Try instantiating your logger in here.
        // (There's a guide for that)
    }
}

Tip

The Sponge documentation provides a guide with more information on events (see Working with Events). Normally, in addition to prefixing event-handler methods with @Listener, you must also register your object with Sponge’s event bus. However, your main plugin class is registered automatically.

State Events

It may also be desirable to listen for other state events, particularly the GameStoppingServerEvent. There are two categories of state events:

• Initialization: These events occur when Sponge and plugins are loading.
  • GameConstructionEvent
  • GamePreInitializationEvent
  • GameInitializationEvent
  • GamePostInitializationEvent
  • GameLoadCompleteEvent
• Running: These events occur when the game and world are loading.
  • GameAboutToStartServerEvent
  • GameStartingServerEvent
  • GameStartedServerEvent
  • GameStoppingServerEvent
  • GameStoppedServerEvent

For information regarding when each state event occurs, see the plugin lifecycle documentation.