How To Use Event Listeners In Java

How the event Listeners work in java,To get the data based on the event occurs in outside the application. I have this method in one of my API class I am not understanding how this methods are going to work.
 
public interface SBXPCXMLEventListener {  
public void OnReceiveEventXML(String eventXML);
}  
private static List<SBXPCXMLEventListener> listenerList = new ArrayList<SBXPCXMLEventListener>();  
protected static void fireXMLEvent(String xml) {  

[Code] ....

I have done like this.This is used to capture the events from the fingerprint machine when run this class I am not getting any data from the machine when i did thumb impression in the machine.

public class EventListnere implements SBXPCXMLEventListener {
    public static void main(String[] args) {
        boolean flag = SBXPCProxy.ConnectTcpip(1, "10.0.0.8", 5005, 1234);
        System.out.println("flag = " + flag);
//        SBXPCProxy.st

[Code] .....