I keep getting this error message when I try to run
----jGRASP exec: java DomParserExample
Exception in thread "main" java.lang.NumberFormatException: null
at java.lang.Integer.parseInt(Integer.java:615)
at DomParserExample.getIntValue(DomParserExample.java:152)
at DomParserExample.getAlbum(DomParserExample.java:111)
at DomParserExample.parseDocument(DomParserExample.java:89)
at DomParserExample.runExample(DomParserExample.java:35)
at DomParserExample.main(DomParserExample.java:177)
----jGRASP wedge2: exit code for process is 1.
----jGRASP: operation complete.
Here is my code that I have written:
Looks like the error is in line 107 but I cant figure it out.
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
public class DomParserExample
{
//No generics
List myAlbums;
Document dom;
public DomParserExample(){
//create a list to hold the employee objects
myAlbums = new ArrayList();
}
public void runExample()
{
//parse the xml file and get the dom object
parseXmlFile();
//get each employee element and create a Employee object
parseDocument();
//Iterate through the list and print the data
printData();
}
private void parseXmlFile()
{
//get the factory
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
try {
//Using factory get an instance of document builder
DocumentBuilder db = dbf.newDocumentBuilder();
//parse using builder to get DOM representation of the XML file
dom = db.parse("albums.xml");
}
catch(ParserConfigurationException pce)
{
pce.printStackTrace();
}
catch(SAXException se)
{
se.printStackTrace();
}
catch(IOException ioe)
{
ioe.printStackTrace();
}
}
private void parseDocument()
{
//get the root elememt
Element docEle = dom.getDocumentElement();
//get a nodelist of <employee> elements
NodeList nl = docEle.getElementsByTagName("album");
if(nl != null && nl.getLength() > 0)
{
for(int i = 0 ; i < nl.getLength();i++)
{
//get the employee element
Element el = (Element)nl.item(i);
//get the Employee object
Album e = getAlbum(el);
//add it to list
myAlbums.add(e);
}
}
}
/**
* I take an employee element and read the values in, create
* an Employee object and return it
* @param empEl
* @return
*/
private Album getAlbum(Element albEl)
{
//for each <employee> element get text or int values of
//name ,id, age and name
String title = getTextValue(albEl,"Title");
String artist = getTextValue(albEl,"Artist");
int year = getIntValue(albEl,"Year");
String category = albEl.getAttribute("category");
//Create a new Employee with the value read from the xml nodes
Album e = new Album(title,artist,year,category);
return e;
}
/**
* I take a xml element and the tag name, look for the tag and get
* the text content
* i.e for <employee><name>John</name></employee> xml snippet if
* the Element points to employee node and tagName is name I will return John
* @param ele
* @param tagName
* @return
*/
private String getTextValue(Element ele, String tagName)
{
String textVal = null;
NodeList nl = ele.getElementsByTagName(tagName);
if(nl != null && nl.getLength() > 0) {
Element el = (Element)nl.item(0);
textVal = el.getFirstChild().getNodeValue();
}
return textVal;
}
/**
* Calls getTextValue and returns a int value
* @param ele
* @param tagName
* @return
*/
private int getIntValue(Element ele, String tagName)
{
//in production application you would catch the exception
return Integer.parseInt(getTextValue(ele,tagName));
}
/**
* Iterate through the list and print the
* content to console
*/
private void printData()
{
System.out.println("No of Albums '" + myAlbums.size() + "'.");
Iterator it = myAlbums.iterator();
while(it.hasNext()) {
System.out.println(it.next().toString());
}
}
public static void main(String[] args)
{
//create an instance
DomParserExample dpe = new DomParserExample();
//call run example
dpe.runExample();
}
}
