Java Language Reading a XML file


Example

In order to load the XML data with XOM you will need to make a Builder from which you can build it into a Document.

Builder builder = new Builder();
Document doc = builder.build(file);

To get the root element, the highest parent in the xml file, you need to use the getRootElement() on the Document instance.

Element root = doc.getRootElement();

Now the Element class has a lot of handy methods that make reading xml really easy. Some of the most useful are listed below:

  • getChildElements(String name) - returns an Elements instance that acts as an array of elements
  • getFirstChildElement(String name) - returns the first child element with that tag.
  • getValue() - returns the value inside the element.
  • getAttributeValue(String name) - returns the value of an attribute with the specified name.

When you call the getChildElements() you get a Elements instance. From this you can loop through and call the get(int index) method on it to retrieve all the elements inside.

Elements colors = root.getChildElements("color");
for (int q = 0; q < colors.size(); q++){
    Element color = colors.get(q);
}

Example: Here is an example of reading an XML File:

XML File:

example of xml

Code for reading and printing it:

import java.io.File;
import java.io.IOException;
import nu.xom.Builder;
import nu.xom.Document;
import nu.xom.Element;
import nu.xom.Elements;
import nu.xom.ParsingException;

public class XMLReader {
    
    public static void main(String[] args) throws ParsingException, IOException{
        File file = new File("insert path here");
        // builder builds xml data
        Builder builder = new Builder();
        Document doc = builder.build(file);
        
        // get the root element <example>
        Element root = doc.getRootElement();
        
        // gets all element with tag <person>
        Elements people = root.getChildElements("person");
        
        for (int q = 0; q < people.size(); q++){
            // get the current person element
            Element person = people.get(q);
            
            // get the name element and its children: first and last
            Element nameElement = person.getFirstChildElement("name");
            Element firstNameElement = nameElement.getFirstChildElement("first");
            Element lastNameElement = nameElement.getFirstChildElement("last");
            
            // get the age element
            Element ageElement = person.getFirstChildElement("age");
            
            // get the favorite color element
            Element favColorElement = person.getFirstChildElement("fav_color");
            
            String fName, lName, ageUnit, favColor;
            int age;
            
            try {
                fName = firstNameElement.getValue();
                lName = lastNameElement.getValue();
                age = Integer.parseInt(ageElement.getValue());
                ageUnit = ageElement.getAttributeValue("unit");
                favColor = favColorElement.getValue();
                
                System.out.println("Name: " + lName + ", " + fName);
                System.out.println("Age: " + age + " (" + ageUnit + ")");
                System.out.println("Favorite Color: " + favColor);
                System.out.println("----------------");
                
            } catch (NullPointerException ex){
                ex.printStackTrace();
            } catch (NumberFormatException ex){
                ex.printStackTrace();
            }
        }
    }
    
}

This will print out in the console:

Name: Smith, Dan
Age: 23 (years)
Favorite Color: green
----------------
Name: Autry, Bob
Age: 3 (months)
Favorite Color: N/A
----------------