Reading Multi-layered XML

[Tien Shan]

I want to use Java and DOM parser. (Not that I know doing it in other language/with SAX, etc.)
I want to get the values of the attributes of the "group" node(?). ("Node" may not be the right nomenclature, please correct if it is not.)
Ex. For "B1" band, grpID attribute is "1" and numStdGrp attribute is "15".

Here is my XML file:

<?xml version="1.0" encoding="UTF-8"?>
<dataHeader 
	><numStudent>150</numStudent>
	<dataMain>
        <band name="B1">
			<group grpID="1" numStdGrp="15"/>
		</band>
		<band name="B2">
			<group grpID="2" numStdGrp="10"/>
		</band>
		<aData size="100000" subj="X Y Z"/>
	</dataMain>
</dataHeader>

What I have done so far:

File fXmlFile = new File("C:\XMLfile");
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(fXmlFile);
doc.getDocumentElement().normalize();

(1) numStudent and dataMain node is easy:
ex.

NodeList nListDM = doc.getElementsByTagName("dataMain");

get node by nListDM.item(0), and use getNodeName() to display name

(2) band node can also be retrieved with getElementsByTagName.

NodeList bListBand = doc.getElementsByTagName("band");
I got bListBand's length = 2, as expected. Also got values of name attributes (B1, B2) as follows:
Node bNodeBand = bListBand.item(0); // the first one
Element bElement = (Element) bNodeBand;
String name = bElement.getAttribute("name")

I am stuck right after this.
How do I get attribute values of the node "group"?
getElementsByTagName(group) is probably bad idea: which band's group? Confusing.

Gurus, please give me some idea.

Thank you for taking time to read and possibly answer.

[William Brogden]

The standard library has methods for all the DOM manipulation methods you need - mostly in the org.w3c.dom package. Check out the nomenclature for the various kinds of Node in the javadocs for the org.w3c.dom.Node class - pay particular attention to the table in the Node documentation.

In your case "band" and "group" are Element nodes so getAttribute( ) will get the attribute value.

Bill

[Tien Shan]

William Brogden:
Thank you for the tips. Yes, it worked!
Let me close this thread.