How to Read XML File in Java

Mohammad Irfan Oct 12, 2023

Java Java File

Sample XML File
Read XML File Using DocumentBuilderFactory in Java
Read XML File in Java POJO
Read XML File Using jdom2 in Java
Read XML File Using XPath in Java
Read XML File Using DOM4J in Java

In this article, we will learn how to parse XML file into Java application by using some libraries such as DOM Parser, XML Parser, jdom2, dom4j, etc. XML stands for Extensible Markup Language, which is used to pass data in an application.

Sample XML File

This is a sample XML file that will be used to read in this article.

<?xml version="1.0"?>
<company>
    <employee id="1001">
        <firstname>Tony</firstname>
        <lastname>Black</lastname>
        <salary>100000</salary>
    </employee>
    <employee id="2001">
        <firstname>Amy</firstname>
        <lastname>Green</lastname>
        <salary>200000</salary>
    </employee>
</company>

Read XML File Using `DocumentBuilderFactory` in Java

We use DocumentBuilder to create an instance for the builder and then parse the XML file using the parse() method. The getElementsByTagName() method fetches each node of the XML, and then each child node of the node is iterated by using the for loop. See the example below.

import java.io.File;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class SimpleTesting {
  public static void main(String[] args) throws ParserConfigurationException, SAXException {
    try {
      File file = new File("company.xml");
      DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
      DocumentBuilder db = dbf.newDocumentBuilder();
      Document document = db.parse(file);
      document.getDocumentElement().normalize();
      System.out.println("Root Element :" + document.getDocumentElement().getNodeName());
      NodeList nList = document.getElementsByTagName("employee");
      System.out.println("----------------------------");
      for (int temp = 0; temp < nList.getLength(); temp++) {
        Node nNode = nList.item(temp);
        System.out.println("\nCurrent Element :" + nNode.getNodeName());
        if (nNode.getNodeType() == Node.ELEMENT_NODE) {
          Element eElement = (Element) nNode;
          System.out.println("Employee id : " + eElement.getAttribute("id"));
          System.out.println("First Name : "
              + eElement.getElementsByTagName("firstname").item(0).getTextContent());
          System.out.println(
              "Last Name : " + eElement.getElementsByTagName("lastname").item(0).getTextContent());
          System.out.println(
              "Salary : " + eElement.getElementsByTagName("salary").item(0).getTextContent());
        }
      }
    } catch (IOException e) {
      System.out.println(e);
    }
  }
}

Output:

Root Element :company
----------------------------
Current Element :employee
Employee id : 1001
First Name : Tony
Last Name : Black
Salary : 100000

Current Element :employee
Employee id : 2001
First Name : Amy
Last Name : Green
Salary : 200000

Read XML File in Java POJO

In case we want to get XML data into Java-compatible type, we can use Java POJO to read data. Here, we use the ArrayList type Employee to add each node using the add() method and then use the for loop to iterate each object. See the below example.

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class Main {
  public static void main(String[] args)
      throws ParserConfigurationException, SAXException, IOException {
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = factory.newDocumentBuilder();
    Document document = builder.parse(new File("employee.xml"));
    List<Employee> employees = new ArrayList<>();
    NodeList nodeList = document.getDocumentElement().getChildNodes();
    for (int i = 0; i < nodeList.getLength(); i++) {
      Node node = nodeList.item(i);
      if (node.getNodeType() == Node.ELEMENT_NODE) {
        Element elem = (Element) node;
        String firstname =
            elem.getElementsByTagName("firstname").item(0).getChildNodes().item(0).getNodeValue();
        String lastname =
            elem.getElementsByTagName("lastname").item(0).getChildNodes().item(0).getNodeValue();
        Double salary = Double.parseDouble(
            elem.getElementsByTagName("salary").item(0).getChildNodes().item(0).getNodeValue());
        employees.add(new Employee(firstname, lastname, salary));
      }
    }
    for (Employee empl : employees) System.out.println(empl.toString());
  }
}
class Employee {
  private String Firstname;
  private String Lastname;
  private double salary;
  public Employee(String Firstname, String Lastname, double salary) {
    this.Firstname = Firstname;
    this.Lastname = Lastname;
    this.salary = salary;
  }
  @Override
  public String toString() {
    return "[" + Firstname + ", " + Lastname + ", " + salary + "]";
  }
}

Output:

[Tony, Black, 100000.0]
[Amy, Green, 200000.0]

Read XML File Using `jdom2` in Java

The jdom2 is a library that provides support of DOM parsing using Java classes. We used SAXBuilder class and build() method to get data into Document and then by using the getRootElement() method, get the elements. See the example below.

import java.io.File;
import java.io.IOException;
import java.util.List;
import javax.xml.parsers.ParserConfigurationException;
import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.JDOMException;
import org.jdom2.input.SAXBuilder;
import org.xml.sax.SAXException;

public class Main {
  public static void main(String[] args)
      throws ParserConfigurationException, SAXException, IOException {
    try {
      File inputFile = new File("/employee.xml");
      SAXBuilder saxBuilder = new SAXBuilder();
      Document document = saxBuilder.build(inputFile);
      System.out.println("Root element :" + document.getRootElement().getName());
      Element classElement = document.getRootElement();

      List<Element> studentList = classElement.getChildren();
      System.out.println("----------------------------");

      for (int temp = 0; temp < studentList.size(); temp++) {
        Element student = studentList.get(temp);
        System.out.println("\nCurrent Element :" + student.getName());
        System.out.println("First Name : " + student.getChild("firstname").getText());
        System.out.println("Last Name : " + student.getChild("lastname").getText());
        System.out.println("Salary : " + student.getChild("salary").getText());
      }
    } catch (JDOMException e) {
      e.printStackTrace();
    } catch (IOException ioe) {
      ioe.printStackTrace();
    }
  }
}

Output:

Root element :company
----------------------------
Current Element :employee
First Name : Tony
Last Name : Black
Salary : 100000

Current Element :employee
First Name : Amy
Last Name : Green
Salary : 200000

Read XML File Using `XPath` in Java

Here, we use the XPath library to parse XML files in Java. The XPathFactory class is used to compile all the nodes into NodeList and then iterate each child through for loop. See the example below.

import java.io.File;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class Main {
  public static void main(String[] args)
      throws ParserConfigurationException, SAXException, IOException {
    try {
      File inputFile = new File("/employee.xml");
      DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
      DocumentBuilder dBuilder;
      dBuilder = dbFactory.newDocumentBuilder();
      Document doc = dBuilder.parse(inputFile);
      doc.getDocumentElement().normalize();
      XPath xPath = XPathFactory.newInstance().newXPath();
      String expression = "/company/employee";
      NodeList nodeList =
          (NodeList) xPath.compile(expression).evaluate(doc, XPathConstants.NODESET);
      for (int i = 0; i < nodeList.getLength(); i++) {
        Node nNode = nodeList.item(i);
        System.out.println("\nCurrent Element :" + nNode.getNodeName());
        if (nNode.getNodeType() == Node.ELEMENT_NODE) {
          Element eElement = (Element) nNode;
          System.out.println("First Name : "
              + eElement.getElementsByTagName("firstname").item(0).getTextContent());
          System.out.println(
              "Last Name : " + eElement.getElementsByTagName("lastname").item(0).getTextContent());
          System.out.println(
              "Salary : " + eElement.getElementsByTagName("salary").item(0).getTextContent());
        }
      }
    } catch (ParserConfigurationException e) {
      System.out.println(e);
    } catch (SAXException e) {
      System.out.println(e);
    } catch (IOException e) {
      System.out.println(e);
    } catch (XPathExpressionException e) {
      System.out.println(e);
    }
  }
}

Output:

Current Element :employee
First Name : Tony
Last Name : Black
Salary : 100000

Current Element :employee
First Name : Amy
Last Name : Green
Salary : 200000

Read XML File Using `DOM4J` in Java

The Dom4j is another library that can parse XML files in Java. The read() method of SAXReader class is used to read nodes into the document. See the example below.

import java.io.File;
import java.io.IOException;
import java.util.List;
import javax.xml.parsers.ParserConfigurationException;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;
import org.xml.sax.SAXException;

public class Main {
  public static void main(String[] args)
      throws ParserConfigurationException, SAXException, IOException {
    try {
      File inputFile = new File("employee.xml");
      SAXReader reader = new SAXReader();
      Document document = reader.read(inputFile);
      System.out.println("Root element :" + document.getRootElement().getName());
      Element classElement = document.getRootElement();
      List<Node> nodes = document.selectNodes("company/employee");
      System.out.println("----------------------------");
      for (Node node : nodes) {
        System.out.println("\nCurrent Element :" + node.getName());
        System.out.println("First Name : " + node.selectSingleNode("firstname").getText());
        System.out.println("Last Name : " + node.selectSingleNode("lastname").getText());
        System.out.println("Salary : " + node.selectSingleNode("salary").getText());
      }
    } catch (DocumentException e) {
      e.printStackTrace();
    }
  }
}

Output:

Root element :company
----------------------------
Current Element :employee
First Name : Tony
Last Name : Black
Salary : 100000

Current Element :employee
First Name : Amy
Last Name : Green
Salary : 200000

Sample XML File

Read XML File Using DocumentBuilderFactory in Java

Read XML File in Java POJO

Read XML File Using jdom2 in Java

Read XML File Using XPath in Java

Read XML File Using DOM4J in Java

Related Article - Java File

Read XML File Using `DocumentBuilderFactory` in Java

Read XML File Using `jdom2` in Java

Read XML File Using `XPath` in Java

Read XML File Using `DOM4J` in Java