How to Update or Modify XML file in Java – JDOM Parser

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Java XML Tutorial

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In this article, we will learn how to update or modify existing XML file in Java using JDOM Parser.

Development Process Steps

1. Existing jdom_users.xml File
2. Program to update existing XML file using JDOM Parser
3. Updated updated_jdom_users.xml File

1. Existing jdom_users.xml File

Let’s say we have below source XML file. We will learn how to modify or edit this XML file with java program using JDOM parser.

<?xml version="1.0" encoding="UTF-8"?>
<Users>
 <User id= "1">
  <firstName>Ramesh</firstName>
  <lastName>Fadatare</lastName>
  <age>28</age>
  <gender>Male</gender>
 </User>
 <User id= "2">
  <firstName>John</firstName>
  <lastName>Cena</lastName>
  <age>45</age>
  <gender>Male</gender>
 </User>
 <User id= "3">
  <firstName>Tom</firstName>
  <lastName>Cruise</lastName>
  <age>40</age>
  <gender>Male</gender>
 </User>
</Users>

We want to change following for every User element in the XML.

• Update all firstName element to block letters.
• Append M for Male and F for Female in ID attribute.
• Remove gender element
• Add new element salary with default value 1000 for each user

2. Program to update existing XML file using JDOM Parser

Here is the java program that does all the above updates using JDOM Parser.

package net.javaguides.javaxmlparser.jdom;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.List;

import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.JDOMException;
import org.jdom2.input.SAXBuilder;
import org.jdom2.output.Format;
import org.jdom2.output.XMLOutputter;

public class UpdateXMLFile {
    public static void main(String[] args) throws JDOMException, IOException {
        // we can create JDOM Document from DOM, SAX and STAX Parser Builder classes
        String fileName = "jdom_users.xml";
        SAXBuilder builder = new SAXBuilder();
        File xmlFile = new File(fileName);
        Document jdomDoc = (Document) builder.build(xmlFile);

        // Get list of User element
        Element rootElement = jdomDoc.getRootElement();
        List < Element > listUserElement = rootElement.getChildren("User");

        // loop through to edit every User element
        for (Element userElement: listUserElement) {

            // change the name to BLOCK letters
            String name = userElement.getChildText("firstName");
            if (name != null)
                userElement.getChild("firstName").setText(name.toUpperCase());

            // edit the ID attribute based on Gender
            String gender = userElement.getChildText("gender");
            if (gender != null && gender.equalsIgnoreCase("female")) {
                String id = userElement.getAttributeValue("id");
                userElement.getAttribute("id").setValue(id + "F");

            } else {
                String id = userElement.getAttributeValue("id");
                userElement.getAttribute("id").setValue(id + "M");
            }

            // remove gender element as it's not needed anymore
            userElement.removeChild("gender");

            // add salary element with default value to every user
            userElement.addContent(new Element("salary").setText("1000"));
        }

        // document is processed and edited successfully, lets save it in new file
        XMLOutputter xmlOutputter = new XMLOutputter(Format.getPrettyFormat());
        // output xml to console for debugging
        // xmlOutputter.output(doc, System.out);
        xmlOutputter.output(jdomDoc, new FileOutputStream("updated_jdom_users.xml"));
    }
}

3. Updated or Modified updated_jdom_users.xml File

<?xml version="1.0" encoding="UTF-8"?>
<Users>
  <User id="1M">
    <firstName>RAMESH</firstName>
    <lastName>Fadatare</lastName>
    <age>28</age>
    <salary>1000</salary>
  </User>
  <User id="2M">
    <firstName>JOHN</firstName>
    <lastName>Cena</lastName>
    <age>45</age>
    <salary>1000</salary>
  </User>
  <User id="3M">
    <firstName>TOM</firstName>
    <lastName>Cruise</lastName>
    <age>40</age>
    <salary>1000</salary>
  </User>
</Users>

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Java XML Tutorial

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