How to do search 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 search child node Employee whose id is 2. Similarly user can search any child 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);

Figure 1

2) 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");

3) 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 Employee that you want to search.

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

• Now get all employee properties as follows.

           String value = element.getElementsByTagName(property_name).item(0).getTextContent();

Software Required:

1. Java
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

<?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


Employee.java


SearchXML.java

Output:

Figure 3

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