Parsing xml in java program

Question

In the following code i M NOT able to understand the use of part of code that is in BOLD
int tableno=tree.getChildCount();
*for(int table=0;table<tableno;table++){*
*if(table==0){*
tree=((DefaultMutableTreeNode)tree.getFirstChild());
*}else{*
tree=((DefaultMutableTreeNode)tree.getNextSibling());
tag1=(Tag)tree.getUserObject();
tableobj=(Table)tag1.getObject();
int rowno=tree.getChildCount();
*for(int rows=0;rows<rowno;rows++){*
*if(rows==0){*
tree=((DefaultMutableTreeNode)tree.getFirstChild());
*}else{*
tree=((DefaultMutableTreeNode)tree.getNextSibling());
tag1=(Tag)tree.getUserObject();
int colno=tree.getChildCount();
*for(int cols=0;cols<colno;cols++){*
*if(cols==0){*
tree=((DefaultMutableTreeNode)tree.getFirstChild());
*}else{*
tree=((DefaultMutableTreeNode)tree.getNextSibling());
tag1=(Tag)tree.getUserObject();
columnobj=(Column)tag1.getObject();
int inner=tree.getChildCount();
*for(int k=0;k<inner;k++){*
*if(k==0){*
tree=((DefaultMutableTreeNode)tree.getFirstChild());
*}else{*
tree=((DefaultMutableTreeNode)tree.getNextSibling());
tag1=(Tag)tree.getUserObject();
*if(tag1.getName().equalsIgnoreCase("image")){*
imagetag=(Images)tag1.getObject();
*if(imagetag.getId().equalsIgnoreCase("3")){*
*if(!lightimage.equals("")) {*
*     imagetag.setURL(lightimage);*
*}*

Answer 1

This is the simplest way to read data from an XML file into a Java program. I have also included some basic error checking, so you can directly cut-paste this code with a few changes ofcourse. All you have to do is change the XML tags within the program to match those that are present in your XML file.
XML File
+<book>+
+<person>+
+<first>Kiran</first>+
+<last>Pai</last>+
+<age>22</age>+
+</person>+
+<person>+
+<first>Bill</first>+
+<last>Gates</last>+
+<age>46</age>+
+</person>+
+<person>+
+<first>Steve</first>+
+<last>Jobs</last>+
+<age>40</age>+
+</person>+
+</book>+
Java Progarm for Parsing the above XML File:
import java.io.File;
import org.w3c.dom.Document;
import org.w3c.dom.*;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
public class ReadAndPrintXMLFile{
public static void main (String argv []){
try {
DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
Document doc = docBuilder.parse (new File("book.xml"));
// normalize text representation
doc.getDocumentElement ().normalize ();
System.out.println ("Root element of the doc is " +
doc.getDocumentElement().getNodeName());
NodeList listOfPersons = doc.getElementsByTagName("person");
int totalPersons = listOfPersons.getLength();
System.out.println("Total no of people : " + totalPersons);
for(int s=0; s<listOfPersons.getLength() ; s++){
Node firstPersonNode = listOfPersons.item(s);
if(firstPersonNode.getNodeType() == Node.ELEMENT_NODE){
Element firstPersonElement = (Element)firstPersonNode;
NodeList firstNameList = firstPersonElement.getElementsByTagName("first");
Element firstNameElement = (Element)firstNameList.item(0);
NodeList textFNList = firstNameElement.getChildNodes();
System.out.println("First Name : " +
((Node)textFNList.item(0)).getNodeValue().trim());
NodeList lastNameList = firstPersonElement.getElementsByTagName("last");
Element lastNameElement = (Element)lastNameList.item(0);
NodeList textLNList = lastNameElement.getChildNodes();
System.out.println("Last Name : " +
((Node)textLNList.item(0)).getNodeValue().trim());
NodeList ageList = firstPersonElement.getElementsByTagName("age");
Element ageElement = (Element)ageList.item(0);
NodeList textAgeList = ageElement.getChildNodes();
System.out.println("Age : " +
((Node)textAgeList.item(0)).getNodeValue().trim());
}//end of if clause
}//end of for loop with s var
}catch (SAXParseException err) {
System.out.println ("** Parsing error" + ", line "
+ err.getLineNumber () + ", uri " + err.getSystemId ());
System.out.println(" " + err.getMessage ());
}catch (SAXException e) {
Exception x = e.getException ();
((x == null) ? e : x).printStackTrace ();
}catch (Throwable t) {
t.printStackTrace ();
//System.exit (0);
}//end of main
There are better implementations of reading XML files which would work for any XML file. The above one would require a few changes every time the XML tag names change. But this is much more simpler than the other programs.