Java Video Tutorial 44
After I made my XML Video Tutorial, you asked me to show you how to parse XML with Java. So, that is what I’m doing in this tutorial.
I wasn’t sure how much to cover, because I could literally create a 5 part series on this topic. I decided to cover the basics in the video and provide another example in the code below.
If you want to see more, tell me and I’ll cover more on parsing XML with Java.
If you like videos like this, please tell Google [googleplusone]
Sharing is always appreciated
Code from the Video
JAVALESSON44.JAVA
// Simple API for XML only allows you to read from an XML
// file. SAX doesn't require you to read the document into memory
import org.xml.sax.*;
// Used to read an XML file into memory where the doc is
// stored as a bunch of objects. You can write back to the file
import org.w3c.dom.*;
// Used to gather XML elements into DOM objects
import javax.xml.parsers.*;
public class Lesson44{
public static void main(String[] args){
// Creates a DOM object in memory. Now you can access
// data in the xml file
Document xmlDoc = getDocument("./src/tvshows5.xml");
// Get the name of the root element
xmlDoc.getDocumentElement();
System.out.println("Root element is " +
xmlDoc.getDocumentElement().getNodeName());
// The nodelist contains all of the nodes in the xml file
NodeList listOfShows = xmlDoc.getElementsByTagName("show");
// Get the number of children in the root element
System.out.println("Number of shows " + listOfShows.getLength());
// The element you want to print out
String elementName = "network";
// The attribute to search for
String attrName = "country";
// Send the NodeList for processing
getElementAndAttrib(listOfShows, elementName, attrName);
// Additional Code not in the Video -------------------
// Returns an Element object represented by the root element
// of the xml file
Element theRoot = xmlDoc.getDocumentElement();
// Get the first child or show element in this situation
Element showElement = (Element)theRoot.getFirstChild();
// Object that will contain all of the show data
tvShow tvs;
// Cycle through all of the show elements until the end
while(showElement != null){
// Go get the first element in show which is name
tvs = getShowData(showElement);
// Print out the value of showName
System.out.println(tvs.showName);
// Get the next show
showElement = (Element)showElement.getNextSibling();
}
}
// Reads an XML file into a DOM document
private static Document getDocument(String docString) {
try {
// API used to convert XML into a DOM object tree
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
// Ignore all of the comments
factory.setIgnoringComments(true);
// Ignore white space in elements
factory.setIgnoringElementContentWhitespace(true);
// Validate the XML as it is parsed
factory.setValidating(true);
// Provides access to the documents data
DocumentBuilder builder = factory.newDocumentBuilder();
// Takes the document
return builder.parse(new InputSource(docString));
}
catch(Exception ex){
System.out.println(ex.getMessage());
}
return null;
}
private static tvShow getShowData(Element ele){
// Returns the first child element in the xml file.
// That element is name
Element nameElement = (Element)ele.getFirstChild();
// Save the value in this element as a String
String showName = getTextValue(nameElement).trim();
// Create a tvShow object that holds the values stored
// in the show elements
return new tvShow(showName);
}
private static String getTextValue(Node theNode) {
// Get the value of the first child element
return theNode.getFirstChild().getNodeValue();
}
private static void getElementAndAttrib(NodeList listOfShows, String elementName, String attrName){
try{
// Cycle through the number of shows
for(int i=0; i < listOfShows.getLength(); i++){
// Get the first show node
Node showNode = listOfShows.item(i);
// Convert into an element to gain access to element methods
Element showElement = (Element)showNode;
// Create a list of nodes that have the name defined in elementName
NodeList networkList = showElement.getElementsByTagName(elementName);
// Get the first and only element in this situation
Element networkElement = (Element)networkList.item(0);
// Returns a list of node elements
// Each value is in a node in side of the network node
// That's why you have to get the child nodes for network
NodeList elementList = networkElement.getChildNodes();
// Check if the element has the attribute set
if(networkElement.hasAttribute(attrName)){
System.out.println(elementName + " : " + ((Node)elementList.item(0)).getNodeValue().trim() +
" has attribute " + networkElement.getAttribute(attrName));
} else {
System.out.println(((Node)elementList.item(0)).getNodeValue().trim());
}
}
}
catch(Exception ex){
System.out.println(ex.getMessage());
}
}
private static class tvShow{
public String showName, showNetwork;
public tvShow(String showName){
this.showName = showName;
}
}
}
XML File I Use
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE tvshow SYSTEM "tvshows5.dtd" >
<?xml-stylesheet type="text/xsl" href="tvshows5.xsl" ?>
<tvshow>
<show>
<name id_code="show_001">Life On Mars</name>
<release>2008</release>
<network country="US">ABC</network>
<description>The series tells the story of New York City police detective Sam Tyler.</description>
<actors>
<actor>
<real_name>Jason O'Mara</real_name>
<character profession="Detective">Sam Tyler</character>
</actor>
<actor>
<real_name>Michael Imperioli</real_name>
<character profession="Detective">Ray Carling</character>
</actor>
</actors>
<poster href="http://ia.media-imdb.com/images/M/MV5BMTM4MDg2NTk1OF5BMl5BanBnXkFtZTcwNzI4OTY5MQ@@._V1._SY317_CR12,0,214,317_.jpg" width="214" height="317" />
<viewers units="million">7.82</viewers>
<end_date>2009</end_date>
</show>
<show>
<name id_code="show_002">Life On Mars</name>
<release>2006</release>
<network country="UK">BBC</network>
<description>The series combines elements of science fiction and police procedural.</description>
<actors>
<actor>
<real_name>John Simm</real_name>
<character profession="Detective">Sam Tyler</character>
</actor>
<actor>
<real_name>Philip Glenister</real_name>
<character profession="Detective">Gene Hunt</character>
</actor>
</actors>
<poster href="http://ia.media-imdb.com/images/M/MV5BMTQxNzc5MjQwNF5BMl5BanBnXkFtZTcwMjU3Njc4Mg@@._V1._SY317_CR8,0,214,317_.jpg" width="214" height="317" />
<viewers units="million">6.8</viewers>
<end_date>2007</end_date>
</show>
<show>
<name id_code="show_003">Freaks and Geeks</name>
<release>1999</release>
<network country="US">ABC</network>
<description>The show centers on a teenage girl, Lindsay Weir, and her brother, Sam, who both attend William McKinley High School during the 1980–1981 school year in the town of Chippewa, Michigan, a fictional suburb of Detroit.</description>
<actors>
<actor>
<real_name>Linda Cardellini</real_name>
<character profession="Student">Lindsay Weir</character>
</actor>
<actor>
<real_name>John Francis Daley</real_name>
<character profession="Student">Sam Weir</character>
</actor>
</actors>
<poster href="http://ia.media-imdb.com/images/M/MV5BMTQ5OTEzODYyMl5BMl5BanBnXkFtZTcwMjcxNTcwMg@@._V1._SY317_CR24,0,214,317_.jpg" width="214" height="317" />
<viewers units="million">6.77</viewers>
<end_date>2000</end_date>
</show>
<show>
<name id_code="show_004">Pushing Daisies</name>
<release>2007</release>
<network country="US">ABC</network>
<description>The series stars Lee Pace as Ned, a pie-maker with the ability to bring dead things back to life with his touch, an ability that comes with stipulations.</description>
<actors>
<actor>
<real_name>Lee Pace</real_name>
<character profession="Baker">Ned</character>
</actor>
<actor>
<real_name>Anna Friel</real_name>
<character profession="Baker">Charlotte Chuck Charles</character>
</actor>
</actors>
<poster href="http://ia.media-imdb.com/images/M/MV5BMTY3ODYxNjU1Nl5BMl5BanBnXkFtZTcwMTI0MTU1MQ@@._V1._SY317_CR0,0,214,317_.jpg" width="214" height="317" />
<viewers units="million">7.78</viewers>
<end_date>2009</end_date>
</show>
</tvshow>
Thanks for sharing, whts your next tutorial series ?
Next I’ll cover OOP design, design patterns, software development and algorithms.
superb bro.
Thank you 🙂 Part 46 is going to be really good
I appreciate the video very much. As a Noob, I spent several hours trying to determine why I was getting a “document not properly formed error”. Turns out that the DTD file is not listed along with the code. I only learned this after a considerable amount of internet research and going to your XML 4 tutorial. Please help Noobs by keeping all the associated code together for each video. But, I also learned more about XML in general during my research on StackOverflow, so its good & bad.
You’re very welcome and thank you for the input 🙂
Fantastic explanation of parsing xml file in JAVA with examples.
Appreciate your lecture whole-heartedly.
You’re very welcome 🙂
Warning: validation was turned on but an org.xml.sax.ErrorHandler was not
set, which is probably not what is desired. Parser will use a default
ErrorHandler to print the first 10 errors. Please call
the ‘setErrorHandler’ method to fix this.
Error: URI=file:///home/niraj/webcode/Lesson44/src/tvshow.xml Line=4: Element type “tvshow” must be declared.
Error: URI=file:///home/niraj/webcode/Lesson44/src/tvshow.xml Line=5: Element type “show” must be declared.
Error: URI=file:///home/niraj/webcode/Lesson44/src/tvshow.xml Line=6: Element type “name” must be declared.
Error: URI=file:///home/niraj/webcode/Lesson44/src/tvshow.xml Line=7: Element type “release” must be declared.
Error: URI=file:///home/niraj/webcode/Lesson44/src/tvshow.xml Line=8: Element type “network” must be declared.
Error: URI=file:///home/niraj/webcode/Lesson44/src/tvshow.xml Line=9: Element type “description” must be declared.
Error: URI=file:///home/niraj/webcode/Lesson44/src/tvshow.xml Line=10: Element type “actors” must be declared.
Error: URI=file:///home/niraj/webcode/Lesson44/src/tvshow.xml Line=11: Element type “actor” must be declared.
Error: URI=file:///home/niraj/webcode/Lesson44/src/tvshow.xml Line=12: Element type “real_name” must be declared.
Error: URI=file:///home/niraj/webcode/Lesson44/src/tvshow.xml Line=13: Element type “character” must be declared.
Root element is tvshow
Number of shows 4
network : ABC has attribute US
network : BBC has attribute UK
network : ABC has attribute US
network : ABC has attribute US
Here is the solution http://stackoverflow.com/questions/1866886/warning-validation-was-turned-on-but-an-org-xml-sax-errorhandler
I replaced the document src with a web address, but I always get a 403 error. How can I get past this?
Actually, never mind. I found out how. The videos are awesome!
Thank you 🙂
You are Awesome !!!….. thanks a ton for all your tutorials…..
please let me know if you have some online tutorials (advanced Java )… to handle very large xml files (somewhere between 1- 5 GB)…
god bless you….
take care…. coz you are very important…
Thank you very much 🙂 I’ll be getting into the web side of Java soon. May God bless you as well.
hi i like your tutorials, they are very helpfull for me!
thank you!
if you can, it will be great to have one tutorial about xml SAX
parser. they are common as well..
take care…
Thank you 🙂 I’ll do my best to cover sax. I get into parsing options in my Android tutorials as well.
Doesn’t like this line:
Element showElement = (Element)theRoot.getFirstChild();
Exception in thread “main” java.lang.ClassCastException: com.sun.org.apache.xerces.internal.dom.DeferredTextImpl cannot be cast to org.w3c.dom.Element
at readingXMLTest.Lesson44.main(Lesson44.java:53)
Casting error. New to this, so a little unsure on what the particulars are between Elements & Nodes… ugh, going to take some reading.
Here is an explanation that may help
Very interesting tutorial.
I have a general question tho.
What would you recommend to use to update the xml element content . Basically , what is the best way to copy one node content to another node?
ex : Just to make it more clear. what would you recommend to copy “Copy me” and replace “text”…hope that makes sense…
Copy me
text
I cover that as the tutorial continues in depth.
Hi,
Thanks a lot for your great tutorial
Is there a way to dl the code ? I can not copy paste the code , it takes some other things with it
You’re very welcome 🙂 If you put your mouse over the top right corner of the code, 3 icons pop up. Click on the one named view source and you’ll get the code without line numbers. Sorry about that
Hi Derek,
Your tutorials are amazing, I am following those since few months, I liked it very very much!Kudos to you for providing such wonderful tutorials that to free! and your efforts for creating those! Lots of blessings to you!
Thanks
Thank you 🙂 I’m very happy that you are enjoying them.