XMLReaderDOM.java

package orderprocessing.service;

import java.util.ArrayList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import orderprocessing.data.Order;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
 
 
public class XMLReaderDOM {
	
	private static XMLReaderDOM instance = null;
	private final String savePath;
	private XMLReaderDOM(){
		savePath="/path/to/orders.xml";
	}
	
	public static XMLReaderDOM getInstance() {
		if(instance == null){
			instance= new XMLReaderDOM();
		}
		return instance;
	}
	
	public Order retrieveOrder(String requiredIndex){
		DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder dBuilder;
        try {
            dBuilder = dbFactory.newDocumentBuilder();
           Document doc = dBuilder.parse(savePath);
           
            Element rootElement = doc.getDocumentElement();
 
            NodeList orderList = rootElement.getElementsByTagName("Order");  

        	System.out.println(orderList.getLength());
            Node orderElement ;
            NodeList children;
            int counter;
            double price = 0;
            String index =null;

            for(int i=0;i<orderList.getLength();i++){
            	orderElement = orderList.item(i);
            	children = orderElement.getChildNodes();
            	counter =0;
            	for(int j=0;j<children.getLength();j++ ){
            		if(children.item(j).getNodeType()==Node.ELEMENT_NODE){
            			if(counter==0){
            				index = children.item(j).getTextContent();
            				counter++;
            			}
            			else
            				price = Double.parseDouble(children.item(j).getTextContent());
            			
            		}
            	} 
            	if(requiredIndex.trim().equals(index)){
            		return new Order(requiredIndex,price);
            	}
            }
            System.out.println("DONE");
 
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
	}
	
	
}