ช่วยแก้ error JAVA Webservice ให้หน่อยค่ะ กำลังศึกษาค่ะแต่ไม่ค่อยเข้าใจ

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.DOMException;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import java.io.IOException;
import java.io.File;
import javax.swing.JOptionPane;

public class DOMRead1 {


	public static void main(String[] args) {
		String filename="customers.xml";
		String output="";
		try{
			DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();//reserve storage area
			DocumentBuilder parser=factory.newDocumentBuilder();//create parser object
			Document doc=parser.parse(new File(filename));//read and check document,safe to document object
			Element  root=doc.getDocumentElement();//declare element for keep root element
			NodeList customerList=root.getElementsByTagName("customer");//has more Contact element
			Element emCustomer,temp;//declare child elements in Contact element
			Node node;
			for(int i=0;i<customerList.getLength();i++){
				
				emCustomer=(Element)customerList.item(i);
				temp=(Element)emCustomer.getElementsByTagName("customer").item(0);
				output+="customer:"+temp.getAttribute("id")+"\n";

				node=temp.getElementsByTagName("Mr").item(0);
				output+=temp.getTagName()+"\n";
				
				NodeList profileList=temp.getElementsByTagName("profile");
				for(int j=0;j<profileList.getLength();j++){
					node=profileList.item(j);
					output+=node.getNodeName()+":"+node.getFirstChild().getNodeValue()+"\n";
				}
				node=temp.getElementsByTagName("occupation").item(0);
				output+="Occupation:"+node.getFirstChild().getNodeValue()+"\n";
				
				temp=(Element)emCustomer.getElementsByTagName("birthplace").item(0);
				output+="Country:"+temp.getAttribute("county")+"\n";
				node=temp.getElementsByTagName("birthplace").item(0);
				output+="Birthplace:"+node.getFirstChild().getNodeValue()+"\n";			
				output+="\n";
				
			}//end loop
			JOptionPane.showMessageDialog(null, output);
			
		}
		catch(DOMException d){
			d.printStackTrace();
		}
		catch(IOException io){
			io.printStackTrace();
		}
		catch(Exception e){
			e.printStackTrace();
		}
		
		
		

	}

}

<?xml version="1.0"?>
<customers>
  <customer id="HO107163">
    <Mr />
    <profile>
      <firstName>Jeff</firstName>
      <middleName>Craig</middleName>
      <lastName>Rafter</lastName>
      <sex>m</sex>
      <age>64</age>
    </profile >
    <occupation >Rector of Ringwould Kent</occupation>
    <birthplace county="KEN">Margate</birthplace>
  </customer>
  <customer id="HO107100">
    <Mr />
    <profile>
      <firstName>Georgiana</firstName>
      <middleName>Georgiana</middleName>
      <lastName>Monins</lastName>
      <sex>f</sex>
      <age>39</age>
    </profile>
    <occupation>Gentlewoman</occupation>
    <birthplace>Canterbury</birthplace>
  </customer>
  <customer id="HO107105">
    <Mr />
    <profile>
      <firstName>Ann</firstName>
      <middleName>Anny</middleName>
      <lastName>Gaslinge</lastName>
      <sex>f</sex>
      <age>39</age>
    </profile>
    <occupation>House servant</occupation>
    <birthplace county="KEN">Staple</birthplace>
  </customer>