Java and the XML DOM, cont.

NodeList Interface Methods

Method                                                Description

int getLength()                                            Gets the number of nodes in this list

Node item(int index)                                      ‑Gets the item at the specified index value in the collection

In Table 11.5, you'll see that the NodeList interface supports a getLength method that returns the number of nodes in the list. This means that we can find how many <CUSTOMER> elements there are in the document like this:

import org.w3c.dom.*;

import org.apache.xerces.parsers.DOMParser;

 

public class FirstParser

{

    public static void main(String[] args)

    {

 

        try {

            DOMParser parser = new DOMParser();

            parser.parse(args[0]);

            Document doc = parser.getDocument();

 

            NodeList nodelist = doc.getElementsByTagName("CUSTOMER");

            System.out.println(args[0] + " has " +

            nodelist.getLength() + " <CUSTOMER> elements.");

 

        } catch (Exception e) {

            e.printStackTrace(System.err);

        }

    }

}

You can see the results of this code here, indicating that customer.xml has three <CUSTOMER> elements, which is correct:

%java FirstParser customer.xml

customer.xml has 3 <CUSTOMER> elements.

If you prefer to use the -classpath switch instead of explicitly setting the class path, you could use javac like this, assuming the needed .jar files are in the current directory:

javac -classpath xerces.jar;xercesSamples.jar FirstParser.java

And then execute the code like this:

javac -classpath xerces.jar;xercesSamples.jar FirstParser customer.xml

That's all it takes to get started with the XML for Java parsers.