Main Plugin Class

Note

The instructions within the Sponge Documentation assume that you have prior knowledge of Java. SpongeAPI 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 SpongeAPI as a dependency is creating a new class. The class can be named however you 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, more detailed usage is explained on Plugin Metadata.

package io.github.username.project;

import org.spongepowered.plugin.builtin.jvm.Plugin;

@Plugin("exampleplugin")
public class ExamplePlugin {

}

Note

Refer to Plugin Identifiers if you’ve not chosen your plugin ID yet.

Initializing Your Plugin

Your plugin can listen for particular events, called lifecycle events, to be notified about changes in the state of the game or be to prompted to peform a specific task, such as registering a command. In the example below, onServerStart(StartedEngineEvent<Server>) is called when the StartedEngineEvent occurs for the Server. Note that the method is annotated with the Listener annotation.

The example below will log a message upon starting the server. If your plugin is correctly loaded, you should see this message as part of the server’s initialization output.

import org.spongepowered.api.event.Listener;
import org.spongepowered.api.event.lifecycle.StartedEngineEvent;
import org.spongepowered.plugin.builtin.jvm.Plugin;

// Imports for logger
import com.google.inject.Inject;
import org.apache.logging.log4j.Logger;

@Plugin("exampleplugin")
public class ExamplePlugin {

    @Inject
    private Logger logger;

    @Listener
    public void onServerStart(final StartedEngineEvent<Server> event) {
        logger.info("Successfully running ExamplePlugin!!!");
    }

}

Tip

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

Lifecycle Events

It may also be desirable to listen for other lifecycle events in your plugin, such that you can react to re-registration requests or engine/game state changes. See the plugin lifecycle documentation for more information on the lifecycle events available for plugins to listen to.