Parse XML file in Java using DOM Parser

In this example, we will parse an XML file using the Java inbuilt DOM (Document Object Model) parser.

<?xml version="1.0" encoding="UTF-8"?>
<students>
  <student>
    <Id>1</Id>
    <Name>Sam</Name>
    <Age>20</Age>
  </student>
  <student>
    <Id>2</Id>
    <Name>Rita</Name>
    <Age>22</Age>
  </student>
  <student>
    <Id>3</Id>
    <Name>Mike</Name>
    <Age>23</Age>
  </student>
  <student>
    <Id>4</Id>
    <Name>Alex</Name>
    <Age>21</Age>
  </student>
</students>

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import java.io.File;
import java.io.IOException;

/**
 * 
 * Code2care Java Programs
 * 
 * This program demonstrates how to parse an
 * XML file using Dom Parser.
 * 
 */
public class JavaDomParserExample {

    public static void main(String[] args) throws ParserConfigurationException, IOException, SAXException {

        DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
        Document document = documentBuilder.parse(new File("/Users/code2care/IdeaProjects/plan/src/sample.xml"));

        String rootNode = document.getDocumentElement().getNodeName();
        NodeList studentsList = document.getElementsByTagName("student");

        for (int i = 0; i < studentsList.getLength(); i++) {

            Element student = (Element) studentsList.item(i);
            String id = student.getElementsByTagName("Id").item(0).getTextContent();
            String name = student.getElementsByTagName("Name").item(0).getTextContent();
            String age = student.getElementsByTagName("Age").item(0).getTextContent();

            System.out.println(rootNode + " record : " +( i + 1));
            System.out.println("Id: " + id);
            System.out.println("Name: " + name);
            System.out.println("Age: " + age);
            System.out.println("--------------");
        }
    }
}

students record: 1
Id: 1
Name: Sam
Age: 20
--------------
students record: 2
Id: 2
Name: Rita
Age: 22
--------------
students record: 3
Id: 3
Name: Mike
Age: 23
--------------
students record: 4
Id: 4
Name: Alex
Age: 21
--------------

1. Create an object of javax.xml.parsers.DocumentBuilderFactory the java core inbuilt XML parser.
2. Create an object of javax.xml.parsers.DocumentBuilder
3. Now, Create the org.w3c.dom.Document object
4. Get the node list using: document.getElementsByTagName("tag-name-here")
5. Iterate over the NodeList and get access to the elements of the xml file.

Note: DOM Parser will load the whole of the XML file in memory, so if the XML file is too huge you should avoid using DOM parser and instead use a SAX parser to avoid OOM (Out of Memory Errors).