如何使用 Java 在 XML 文件中搜索关键字？

Question

I would like to use Java to search an XML file for the word "Smith" and print in the console "Smith, Mike"

<?xml version = "1.0"?>
<class>
   <student rollno = "1">
      <firstname>Doe</firstname>
      <lastname>Jane</lastname>
   </student>
   
   <student rollno = "2">
      <firstname>Smith</firstname>
      <lastname>Mike</lastname>
   </student>
   
   <student rollno = "3">
      <firstname>Fonda</firstname>
      <lastname>Jane</lastname>
   </student>
</class>

I've found resources online to query the whole XML file but had difficulty finding ways to search inside the tags.

Answer 1

try with following solution. in this example used the DOM Parser for parse XML file.

String firstName = "";
Scanner scanner = new Scanner(System.in);

System.out.print("Enter the first name: ");
firstName = scanner.nextLine();
        
try {
    File inputFile = new File("input.xml");
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = factory.newDocumentBuilder();
    Document document = builder.parse(inputFile);
    document.getDocumentElement().normalize();
    NodeList nodeList = document.getElementsByTagName("student");
    for (int i = 0; i < nodeList.getLength(); i++) {
        Element element = (Element) nodeList.item(i);
        if(element.getElementsByTagName("firstname").item(0).getTextContent().equals(firstName)){
            System.out.println("Full Name : "+element.getElementsByTagName("firstname").item(0).getTextContent()+" "+
                                                    element.getElementsByTagName("lastname").item(0).getTextContent());
            break;
        }
    }
} catch (Exception e) {
    e.printStackTrace();
}

console output,

Enter the first name: Smith
Full Name : Smith Mike // when enter the first name as "Smith"