What's not understood in DOM parsing?

p506025

<! DOCTYPE db-config SYSTEM "db-config.dtd">
<db-config>
<db-info id = "oracle">
<db-driver> oracle.jdbc.driver.OracleDriver </ db-driver>
<db-url> jdbc: oracle: thin: @ 192.168.1.78: 1521: ORDBA </ db-url>
<db-userName> scott </ db-userName>
<db-userPassword> tiger </ db-userPassword>
</ db-info>
<db-info id = "mysql">
<db-driver> com.mysql.jdbc.Driver </ db-driver>
<db-url> jdbc: mysql: // localhost: 3306 / jive? useUnicode = true&amp; characterEncoding = UTF-8 </ db-url>
<db-userName> root </ db-userName>
<db-userPassword />
</ db-info>
</ db-config>

I used the DOM to parse the xml document shown above, but there was a rather depressed place
I use
Element root = doc.getDocumentElement ();
Get the root element, next I use
NodeList nodeList = root.getElementsByTagName ("db-info");
To get its "db-info" child nodes,
It stands to reason that I continue to get its
NodeList nodeChileList = lement.getElementsByTagName ("db-driver");
But why use it when getting the "db-driver" element:
nodeChileList.item (0) .getFirstChild (). getNodeValue () method?
Instead of using the nodeChileList.item (0) .getNodeValue () method directly?
The getFirstChild () method is literally understood to get its first child node ???

p_n_s_h

The same question

i506025

Because dom regards the content of the element as a Node
nodeChileList.item(0) gets an element node
nodeChileList.item(0).getFirstChild(). Get the content node of the element