XML DOM

[Madhusudan Rao]

How do you traverse through XML DOM using Java ?

[Deepika Wadhwa]

There are so many XML DOM parser are available, at free of cost too.These parsers provide API for reading, extracting, editing data to and from a XML file in a very simple format in java language.
Mostly used DOM parsers are from Sun, IBM 's XML 4j , apaches xerces comes with IBM's parsers itself.
what basically parsers do , it allows you to traverse the XML file as a document in tree structure . you can easily create root node, add nodes to that ,add elements ,add attributes etc using different methods in Java.
i hope how it should make some sense to you.
thanx
Deepika

[Anil Vupputuri]

Do u want to work with DOM..
Follow the link for DOM tutorial.. http://java.sun.com/xml/docs/tutorial/dom/index.html
Anil

[This message has been edited by Anil Vupputuri (edited January 23, 2001).]

[Mike Scheer]

Madhusudan,
I have written some code in java (IBM Visual Age) and traverse through the DOM to read in data. I start at the root element then get it's child nodes. Loop through the child nodes (and their children if applicable until you find a data holding element). IBM's parser has the methods getChildNodes() and getNodeName(). When you come upon that particular data holding element, extract the data. Inserting the data at this point into a data holding object makes sense.
You can loop through the XML DOM using hard coded values for the data element names you are seeking if you wish. I have used a recursive method to continue my search for the correct child node. (I get a list of data holding elements by reading in the DTD and adding the data holding element names to a list. I then compare this list to hard coded values in a data object as a check to see if the XML data will synch up with my data object):
protected void traverseDocumentNodes(node){
.............
.............
psuedo code if(node.element name != to data holding element names in my list){
traverseDocumentNodes(child node)
else
get the node's value and add to data object
}
}
The above is great when you have different levels of nesting of elements and data.
Hope this is of some use.

[Frank Carver]

Depending on which data you wish to extract, there may be simpler methods, too. I have occasionally used a generic DOM-traverser to build a properties file in a simple "dotted" naming convention which then alows direct access to values if you know the structure. For example, the XML

<?xml version="1.0"?>
<root>
 <context>example</context>
 <child seq="1">
  <name>First</name>
  <value>initial text</value>
 </child>
 <child seq="2">
  <name>Second</name>
  <value>subsequent value</value>
 </child>
</root>

would become something like:

root.context=example
root.child.@seq=1
root.child.name=First
root.child.value=initial text
root.child~1.@seq=2
root.child~1.name=Second
root.child~1.value=subsequent value

Single values may then be fetched with a single access like
xml.getProperty("root.context");
and looping through multiple children is not hard either.