<!ELEMENT DOCUMENT (CUSTOMER)*> in .NET framework

Scanner QR Code in .NET framework <!ELEMENT DOCUMENT (CUSTOMER)*>

This means we can't just loop over the root element's children like this: Element root = dgetRoot();

Enumeration enum = rootgetChildren();

while (enumhasMoreElements()) {

Element elem2 = (Element)enumnextElement();

If we used the above code, we'd just loop over the root element's immediate children Instead, we want to loop over all children in the document, and that will take a little thought We start with the root element, <DOCUMENT>: <DOCUMENT>

None of those elements have attributes, however, so we go back up the tree to find the next tag, <DATE>: <DOCUMENT>

When we're done with those elements, we move back one level and examine the elements of the next branch of the tree: <DOCUMENT>

The pattern is clear: we start at a particular element, display its attributes (if any), and then loop over all its children If we reach a child element that has children itself, we have to loop over those children How will we do this in code We'll set up a new method named doTree() to handle this process This method displays the current element's attributes[md]and then loops over the element's children, calling itself (ie, the doTree() method) for the each child The doTree() method handles each child by printing the child's attributes And if the child has children, it loops over the children as well After all the children have been examined, we return to the original element and then return to the code that called the method, which may itself have been the same method calling itself from a higher level This process[md]a method calling itself[md]is called recursion, and it's a fundamental technique of XML browsers, as we'll see in the next chapter Using recursion, we can work through the entire element tree, traveling down one branch to its end, moving back up that branch, and continuing to the next one All we have to do is handle the current element by displaying its attributes, and then loop over all its children, having the method call itself That's how doTree() will work We will add another refinement to doTree(): to make the structure of the tree more evident, we'll indent the elements as we display them, just as they appear in the attlistxml file:

call doTree(), we simply add four more spaces to the indentation string When we print the attributes of each element, we'll simply preface those attributes' text with the indentation string Let's see this in action Our first step is to call doTree() with the root element to start things off Note that we pass an empty string ("") as the indentation string for the root element, because we don't want that element to appear indented: import commsxmlParseException;

import commsxmlDocument;

import commsxmlElement;

import javautilEnumeration;

import javaio*;

import javaioPrintStream;

import javanet*;

static String filename;

public static void main(String args[])

filename = "file:////c://xml//attlist//attlistxml";

catch (ParseException e) {

dreportError(e, Systemout);

if (d != null) {

doTree(dgetRoot(), "");

Now let's write our recursive method, doTree()

The doTree() method takes an Element and a String: import commsxmlParseException;

import commsxmlDocument;

import commsxmlElement;

import javautilEnumeration;

import javaio*;

import javaioPrintStream;

import javanet*;

static String filename;

public static void main(String args[])

static void doTree(Element elem, String indent)

This method has two purposes: to display the attributes of the current element and to loop over its children (if any), calling itself again and again as needed to process the children We'll start by displaying the current element's attributes, and the first step in doing so is to get an enumeration of those attributes We do that with the Element class' getAttributes() method, which returns an enumeration of the current element's attributes: import commsxmlParseException;

import commsxmlDocument;

import commsxmlElement;

import javautilEnumeration;

import javaio*;

import javaioPrintStream;

import javanet*;