Sum in XPath in Java XML

Create new package named data. In this package, create new xml file named products.xml as below:

<?xml version="1.0" encoding="UTF-8"?>
<products>
	<product>
		<id>p01</id>
		<name>name 1</name>
		<price currency="usd">20</price>
		<quantity>5</quantity>
		<weight unit="kg">2.1</weight>
		<date format="dd/MM/yyyy">02/03/2017</date>
		<status>true</status>
	</product>
	<product>
		<id>p02</id>
		<name>name 2</name>
		<price currency="eur">12</price>
		<quantity>3</quantity>
		<weight unit="kg">6.5</weight>
		<date format="dd/MM/yyyy">24/11/2018</date>
		<status>true</status>
	</product>
	<product>
		<id>p03</id>
		<name>name 3</name>
		<price currency="aud">13</price>
		<quantity>1</quantity>
		<weight unit="kg">7.8</weight>
		<date format="dd/MM/yyyy">14/10/2018</date>
		<status>false</status>
	</product>
</products>

Create new package, named demo. In this package, create new java class, named Main as below

package demo;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;

public class Main {

	private static void sum() {
		try {
			DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
			DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
			Document document = documentBuilder.parse("src\\data\\products.xml");
			XPath xpath = XPathFactory.newInstance().newXPath();
			int result = Integer.parseInt(xpath.compile("sum(//quantity)").evaluate(document));
			System.out.println("Quantities: " + result);
		} catch (Exception e) {
			System.err.println(e.getMessage());
		}
	}

	public static void main(String[] args) {

		sum();

	}

}

Quantities: 9