How to add new attribute to the 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 each Employee node has only one attribute id. But now my requirement is to add another attribute say yyy="xxx" to Employee whose id is 2. Similarly user can add any attribute to any given Employee node.

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, attribute name and attribute value. Here node means Employee.

Add new attribute to given node in XML file using DOM Parser

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 add its attribute as follows.

element.setAttribute(attribute, value);

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:

JDK
Eclipse
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

<?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>

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; } }

AddEmployeeAttribute.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 AddEmployeeAttribute { 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 attribute name : "); String attribute=input.readLine(); System.out.println("Enter attribute value : "); String value=input.readLine(); boolean result=addEmployeeAttributeInXml(document,id,attribute,value); 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 attribute has been added successfully."); } else { System.out.println("Employee not exist."); } } finally { if(input!=null){ input.close(); } } } private static boolean addEmployeeAttributeInXml(Document document, int id, String attribute, String value) { 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))) { element.setAttribute(attribute, value); result=true; break; } } } return result; } }

Output:

Figure 3

employee.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<Employees>
<Employee id="1" nationality="indian">
<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>

Here you can see that attribute nationality="indian" has been added for Employee whose id is 1.

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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.

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