How to delete child node of given node in XML file using DOM Parser in Java?

Problem Description:

Suppose we have following XML file as an example.

<Employees>

   <Employee id="1">
       <name>abc</name>
       <age>23</age>
   </Employee >
  <Employee id="2">
       <name>xyz</name>
       <age>29</age>
   </Employee>
   <Employee id="3">
       <name>lmn</name>
       <age>34</age>
   </Employee>

</Employees>

Here requirement is to delete child node <age>34</age> for Employee whose id is 3.  Similarly user can delete any child node for any Employee.

Steps:

1) Parse XML file or Create an instance of Document interface present in org.w3c.dom.* package.

For Creating an instance of Document interface we need to use DocumentBuilderFactory, DocumentBuilder classes present in javax.xml.parsers.* package and File class present in java.io.* package.

File file = new File(XML_file_location);

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

DocumentBuilder builder = factory.newDocumentBuilder();

Document document = builder.parse(file);

2) Enter node id, child name. Here node means Employee and child means property of Employee.

Figure 1

3) Get all the child nodes Employee of root node Employees. It returns the instance of NodeList interface present in org.w3c.dom.* package.

NodeList list = document.getElementsByTagName("Employee");

4) Now one by one examine each child node Employee.

• From all the child nodes that we got in Step 3 take one child node. It returns instance of Node interface present in org.w3c.dom.* package.

          Node node = list.item(i);

• Check whether this node is Element node or not?

          if (node.getNodeType() == Node.ELEMENT_NODE) { }

• If it is an Element node then typecast it and get its data (attributes and properties).

          Element element = (Element) node;

• Get its id as follows.

          String id=element.getAttribute("id");

• Compare this id with id of given Employee.

         if (String.valueOf(id).equals(element.getAttribute("id"))) {}

• If id found then check whether given child node exists or not.

           Node current = element.getElementsByTagName(property).item(0);

• If child node exists then get previous sibling of child node as follows.

          Node prev = current.getPreviousSibling();

• If sibling is text node then delete it from given node Employee.

          if (prev != null && prev.getNodeType() == Node.TEXT_NODE && prev.getNodeValue().trim().length() == 0) {

element.removeChild(prev);

}

• Now delete selected child node from given node Employee.

          element.removeChild(current);

5) Create an instance of Transformer class present in javax.xml.transform.* package. 

For creating an instance of Transformer class we need to use TransformerFactory class present in javax.xml.transform.* package.

TransformerFactory tFactory = TransformerFactory.newInstance();
Transformer transformer = tFactory.newTransformer();

6) Set xml file indentation (Optional)

transformer.setOutputProperty(OutputKeys.INDENT, "yes");

7) Create an instance of DOMSource class present in javax.xml.transform.dom.* package and pass instance of Document interface created in step 1.

DOMSource source = new DOMSource(document);

8) Create an instance of StreamResult class present in javax.xml.transform.stream.* package.

For creating an instance of StreamResult class first we need to create an instance of File class present in java.io.* package.

File file = new File(location_of_xml_file);
StreamResult result = new StreamResult(file);

9) Transform XML Source to a Result.

transformer.transform(source, result);

Software Required:

1. JDK
2. Eclipse
3. Maven

Note : I suggest to use latest version of all the software. If you need any help regarding these software installation please comment below I will help you.

Project Structure:

Figure 2

Java Code:


  employee.xml

12345678910111213141516<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<Employees>
<Employee id="1">
<name>Rohit</name>
<gender>male</gender>
<age>25</age>
<role>Programmer</role>
</Employee>
<Employee id="2">
<name>Bhavna</name>
<gender>female</gender>
<age>20</age>
<role>Student</role>
</Employee>
</Employees>

pom.xml

	<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.javamultiplex</groupId>
	<artifactId>DOM</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<build>
	<pluginManagement>
	<plugins>
	<plugin>
	<groupId>org.apache.maven.plugins</groupId>
	<artifactId>maven-compiler-plugin</artifactId>
	<version>3.6.1</version>
	<configuration>
	<source>1.8</source>
	<target>1.8</target>
	</configuration>
	</plugin>
	</plugins>
	</pluginManagement>
	</build>
	</project>

view raw pom.xml hosted with ❤ by GitHub

Employee.java

	package com.javamultiplex;
	public class Employee {
	private int id;
	private String name;
	private int age;
	private String gender;
	private String role;
	public String getName() {
	return name;
	}
	public void setName(String name) {
	this.name = name;
	}
	public int getAge() {
	return age;
	}
	public void setAge(int age) {
	this.age = age;
	}
	public String getGender() {
	return gender;
	}
	public void setGender(String gender) {
	this.gender = gender;
	}
	public String getRole() {
	return role;
	}
	public void setRole(String role) {
	this.role = role;
	}
	@Override
	public String toString() {
	return "Employee[id="+getId()+", name="+getName()+", gender="+getGender()+", age="+getAge()+", role="+getRole()+"]";
	}
	public int getId() {
	return id;
	}
	public void setId(int id) {
	this.id = id;
	}
	}

view raw Employee.java hosted with ❤ by GitHub

DeleteEmployeeProperty.java

	package com.javamultiplex;
	import java.io.BufferedReader;
	import java.io.File;
	import java.io.IOException;
	import java.io.InputStreamReader;
	import javax.xml.parsers.DocumentBuilder;
	import javax.xml.parsers.DocumentBuilderFactory;
	import javax.xml.parsers.ParserConfigurationException;
	import javax.xml.transform.OutputKeys;
	import javax.xml.transform.Transformer;
	import javax.xml.transform.TransformerException;
	import javax.xml.transform.TransformerFactory;
	import javax.xml.transform.dom.DOMSource;
	import javax.xml.transform.stream.StreamResult;
	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 DeleteEmployeeProperty {
	public static void main(String[] args) throws IOException,ParserConfigurationException, SAXException, TransformerException {
	File file = new File("src/main/resources/employee.xml");
	BufferedReader input = null;
	try {
	input = new BufferedReader(new InputStreamReader(System.in));
	DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
	DocumentBuilder builder = factory.newDocumentBuilder();
	Document document = builder.parse(file);
	System.out.println("Enter employee id : ");
	int id = Integer.parseInt(input.readLine());
	System.out.println("Enter property name : ");
	String property = input.readLine();
	boolean result = deleteEmployeePropertyFromXml(document, id, property);
	if (result) {
	TransformerFactory tFactory = TransformerFactory.newInstance();
	Transformer transformer = tFactory.newTransformer();
	transformer.setOutputProperty(OutputKeys.INDENT, "yes");
	DOMSource source = new DOMSource(document);
	StreamResult sResult = new StreamResult(file);
	transformer.transform(source, sResult);
	System.out.println("Employee property has been deleted successfully.");
	} else {
	System.out.println("Either employee id or property name is wrong.");
	}
	} finally {
	if (input != null) {
	input.close();
	}
	}
	}
	private static boolean deleteEmployeePropertyFromXml(Document document,int id, String property) {
	NodeList list = document.getElementsByTagName("Employee");
	boolean result = false;
	int length = list.getLength();
	for (int i = 0; i < length; i++) {
	Node node = list.item(i);
	if (node.getNodeType() == Node.ELEMENT_NODE) {
	Element element = (Element) node;
	if (element.getAttribute("id").equals(String.valueOf(id))) {
	Node current = element.getElementsByTagName(property).item(0);
	if (current != null) {
	Node prev = current.getPreviousSibling();
	if (prev != null && prev.getNodeType() == Node.TEXT_NODE && prev.getNodeValue().trim().length() == 0) {
	element.removeChild(prev);
	}
	element.removeChild(current);
	result = true;
	break;
	}
	}
	}
	}
	return result;
	}
	}

view raw DeleteEmployeeProperty.java hosted with ❤ by GitHub

Output:

Figure 3

employee.xml

123456789101112131415 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
<Employees>
<Employee id="1">
<name>Rohit</name>
<gender>male</gender>
<age>25</age>
<role>Programmer</role>
</Employee>
<Employee id="2">
<name>Bhavna</name>
<gender>female</gender>
<role>Student</role>
</Employee>
</Employees>

Here you can see that child node <age>20</age> has been deleted for Employee whose id is 2.

Download Project


Click here for more questions on DOM Parser.

References:

https://docs.oracle.com/javase/7/docs/api/javax/xml/parsers/DocumentBuilderFactory.html
https://docs.oracle.com/javase/7/docs/api/javax/xml/parsers/DocumentBuilder.html

https://docs.oracle.com/javase/7/docs/api/org/w3c/dom/Document.html

https://docs.oracle.com/javase/7/docs/api/org/w3c/dom/Element.html

https://docs.oracle.com/javase/7/docs/api/javax/xml/transform/TransformerFactory.html

https://docs.oracle.com/javase/7/docs/api/javax/xml/transform/Transformer.html

https://docs.oracle.com/javase/7/docs/api/java/io/File.html

https://docs.oracle.com/javase/7/docs/api/javax/xml/transform/dom/DOMSource.html

https://docs.oracle.com/javase/7/docs/api/javax/xml/transform/stream/StreamResult.html

Thank you friends, I hope you have clearly understood the solution of this problem. If you have any doubt, suggestion or query please feel free to comment below. You can also discuss this solution in our forum.

About Author:

I am simple guy with lot of ambitions. My main motive is to share whatever knowledge I have related to programming. With me you can easily learn how to solve any programming problem in Java.You can connect with me on social networking sites also.

Let's Get Connected: Linkedin | Facebook | Google Plus