Bukkit

// Delimiter constant to signal end-of-message
#define delimiter "\n"
// This will store incoming messages
String recieved = "";
void setup(){
  // Open the serial port
  Serial.begin(9600);
}
void loop(){
}
// This is called whenever there is incoming data
void serialEvent(){
  // Read the incoming data
  char append = Serial.read();
  // Append the character to our string
  recieved += append;
  // Check for a newline, signaling that the message is complete
  if(recieved.endsWith(delimiter)){
    // Remove the newline
    recieved.replace(delimiter, "");
    recieved.trim();
    // Echo the complete message
    Serial.println(recieved);
    // Reset the message
    recieved = "";
  }
}

import org.bukkit.Bukkit;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import com.shortcircuit.mcinteractive.events.MCIMessageReceivedEvent;
import com.shortcircuit.mcinteractive.events.MCISerialConnectEvent;
import com.shortcircuit.mcinteractive.events.MCISerialDisconnectEvent;
import com.shortcircuit.mcinteractive.events.MCISerialPortEvent;

public class MCIEventListener implements Listener{
    @EventHandler
    public void onConnect(final MCISerialConnectEvent event) {
        Bukkit.getLogger().info("Connected to " + event.getCommPortIdentifier().getName());
    }
    @EventHandler
    public void onDisconnect(final MCISerialDisconnectEvent event) {
        Bukkit.getLogger().info("Disconnected from " + event.getCommPortIdentifier().getName());
    }
    @EventHandler
    public void onEvent(final MCISerialPortEvent event) {
        Bukkit.getLogger().info("Event from " + event.getCommPortIdentifier().getName());
    }
    @EventHandler
    public void onMessage(final MCIMessageReceivedEvent event) {
        Bukkit.getLogger().info("Message from " + event.getCommPortIdentifier().getName()
                + ": " + event.getMessage());
    }
}