Question

3. Write a Java program that loads a gallery.xml file, determines the number of photos (should be only 3) in it and prints out the number of photos in the gallery.

Answer 1

gallery.xml

<?xml version = "1.0" ?>

<gallery>
  <photo id="1">
    <name>Image One</name>
    <size unit="KB">500</size>
  </photo>
  <photo id="2">
    <name>Image Two</name>
    <size unit="KB">587</size>
  </photo>
  <photo id="3">
    <name>Image Three</name>
    <size unit="KB">452</size>
  </photo>
</gallery>

Main.java

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
 
class Main{
 
    public static void main(String[] args) throws IOException {
        String inputFile = "gallery.xml";
 
        try {
            // Reads text from a character-input stream
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
 
            // Defines a factory API that enables applications to obtain a parser that produces DOM object trees from XML documents.
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
 
            // The Document interface represents the entire HTML or XML document. Conceptually, it is the root of the document tree, and provides the primary access to the document's data.
            Document doc = factory.newDocumentBuilder().parse(inputFile);
 
            // Returns a NodeList of all the Elements in document order with a given tag name (photo) and are contained in the document.
            NodeList nodes = doc.getElementsByTagName("photo");
            System.out.println("\nTotal # of Photos in gallery => " + nodes.getLength() + "\n");
 
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}

Output: