Examples

JDA (Java Discord API)

First we need to create our command object, complete with its @CommandDescription annotation.

import com.github.rainestormee.jdacommand.AbstractCommand;
import com.github.rainestormee.jdacommand.CommandAttribute;
import com.github.rainestormee.jdacommand.CommandDescription;
import net.dv8tion.jda.core.entities.Message;

@CommandDescription(
   name = "echo",
   triggers = {"echo", "repeat", "copy"},
   description = "This command echoes what you say!",
   attributes = {@CommandAttribute(key = "args", value = "1")}
)
public class EchoCommand implements AbstractCommand<Message> {

   @Override
   public void execute(Message message, String args) {
      message.getChannel().sendMessage(args).queue();
   }
}

And now we can write a listener to handle the messages coming in from Discord!

import com.github.rainestormee.jdacommand.CommandHandler;
import net.dv8tion.jda.api.entities.Message;
import net.dv8tion.jda.api.events.message.guild.GuildMessageReceivedEvent;
import net.dv8tion.jda.api.hooks.ListenerAdapter;

import javax.annotation.Nonnull;

public class EventHandler extends ListenerAdapter {

   private CommandHandler<Message> handler;
   private String commandTrigger;

   public EventHandler(CommandHandler<Message> handler, String commandTrigger) {
      this.handler = handler;
      this.commandTrigger = commandTrigger;
   }

   @Override
   public void onGuildMessageReceived(@Nonnull GuildMessageReceivedEvent event) {
      String msg = event.getMessage().getContentRaw();
      if (!msg.startsWith(commandTrigger)) return;
         String firstword = msg.split("\\s+")[0].replaceFirst(commandTrigger, "");
         handler.findAndExecute(firstword, event.getMessage(), msg.replaceFirst(msg.split("\\s+")[0], ""));
      }
}

And finally we can register everything when we build our JDA object!

CommandHandler<Message> handler = new CommandHandler<>();
handler.registerCommand(new EchoCommand());
try {
   JDA jda = new JDABuilder().setToken("y0urs3cr3tt0k3nh3r3").addEventListeners(new EventHandler(handler, "!")).build();
} catch (LoginException e) {}