Total.java

package org.softlang.company.features;

import org.apache.xpath.XPathAPI;

import org.w3c.dom.Document; // DOM trees
import org.w3c.dom.Element; // DOM subtrees
import org.w3c.dom.NodeList; // Lists of DOM subtrees

/**
 * Compute the total all salaries of a company
 */
public class Total {

    public static double total(Document doc) 
        throws Exception {

        // The aggregation variable 
        double total = 0;

        // Get the matching elements
        NodeList nodelist = XPathAPI.selectNodeList(doc, "//salary");

        // Process the elements in the nodelist
        for (int i=0; i<nodelist.getLength(); i++) {
            // Get element
            Element elem = (Element)nodelist.item(i);
            total += Double.parseDouble(elem.getTextContent());
        }
        return total;
    }

}