Java Video Tutorial 46
Today I introduce the easiest way to read and write to XML files using Java. It is call the JDOM2 library. With it you’ll easily read any element, or attribute and create your own.
I introduce 10 libraries and show you numerous methods that will make your life easier in just 14 minutes!
All of the code follows the video to improve the learning process.
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Code from the Video
// Class that will represent a system file name
import java.io.File;
// Used to write data to a file
import java.io.FileOutputStream;
// Triggered when an I/O error occurs
import java.io.IOException;
// Represents your XML document and contains useful methods
import org.jdom2.Document;
// Represents XML elements and contains useful methods
import org.jdom2.Element;
// Top level JDOM exception
import org.jdom2.JDOMException;
// Represents text used with JDOM
import org.jdom2.Text;
// Creates a JDOM document parsed using SAX Simple API for XML
import org.jdom2.input.SAXBuilder;
// Formats how the XML document will look
import org.jdom2.output.Format;
// Outputs the JDOM document to a file
import org.jdom2.output.XMLOutputter;
public class Lesson46 {
public static void main(String[] args) {
// writeXML();
readXML();
}
private static void readXML(){
SAXBuilder builder = new SAXBuilder();
try {
// Parses the file supplied into a JDOM document
Document readDoc = builder.build(new File("./src/jdomMade.xml"));
// Returns the root element for the document
System.out.println("Root: " + readDoc.getRootElement());
// Gets the text found between the name tags
System.out.println("Show: " + readDoc.getRootElement().getChild("show").getChildText("name"));
// Gets the attribute value for show_id assigned to name
System.out.println("Show ID: " + readDoc.getRootElement().getChild("show").getChild("name").getAttributeValue("show_id") + "\n");
Element root = readDoc.getRootElement();
// Cycles through all of the children in show and prints them
for (Element curEle : root.getChildren("show")) {
System.out.println("Show Name: " + curEle.getChildText("name"));
System.out.println("Show ID: " + curEle.getChild("name").getAttributeValue("show_id"));
System.out.print("On " + curEle.getChildText("network") + " in the ");
System.out.println(curEle.getChild("network").getAttributeValue("country") + "\n");
}
}
catch (JDOMException e) {
e.printStackTrace();
}
catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private static void writeXML(){
try{
// Creates a JDOM document
Document doc = new Document();
// Creates a element named tvshows and makes it the root
Element theRoot = new Element("tvshows");
doc.setRootElement(theRoot);
// Creates elements show and name
Element show = new Element("show");
Element name = new Element("name");
// Assigns an attribute to name and gives it a value
name.setAttribute("show_id", "show_001");
// Adds text between the name tags
name.addContent(new Text("Life On Mars"));
Element network = new Element("network");
network.addContent(new Text("ABC"));
network.setAttribute("country", "US");
// Adds name and network to the show tag
show.addContent(name);
show.addContent(network);
// Adds the show tag and all of its children to the root
theRoot.addContent(show);
// Add a new show element like above
Element show2 = new Element("show");
Element name2 = new Element("name");
name2.setAttribute("show_id", "show_002");
name2.addContent(new Text("Freaks and Geeks"));
Element network2 = new Element("network");
network2.addContent(new Text("ABC"));
network2.setAttribute("country", "US");
show2.addContent(name2);
show2.addContent(network2);
theRoot.addContent(show2);
// Uses indenting with pretty format
XMLOutputter xmlOutput = new XMLOutputter(Format.getPrettyFormat());
// Create a new file and write XML to it
xmlOutput.output(doc, new FileOutputStream(new File("./src/jdomMade.xml")));
System.out.println("Wrote to file");
}
catch (Exception e) {
e.printStackTrace();
}
}
}
/* Installing JDOM
*
* Download jdom.jar https://github.com/hunterhacker/jdom/downloads
* Download jdom-2.0.2.zip
*
* Right click default eclipse directory - Build Path
*
* Click Java Build Path
*
* Click Libraries tab - external libraries
*
* Add the JDOM libraries
*
*
* */
Hi,
Very, very nice Tutorial. I did not know anything of that. But now I can write and read XML easily.
One simple Question: When I want to write for example the country more than once (with different content), do I have to define a new Element or could I use the created one?
answer at mail please 🙂
Best regards,
Joel
You’re very welcome 🙂 You don’t need to create a separate element, but instead use the one that is already there. Experiment a bit and you’ll really get the concept
Hi Derek, how it’s different from dom parsing ?? I feel there is no difference then why jdom ?? Can you throw some light on this ?
I’m going to cover the web aspects of Java very soon. Sorry I can’t make the videos any quicker
Hi Derek, this is an off-topic question, but still I want to ask. In your videos I see how quickly you type/replace/fill in some things, I do know about ctrl+space combination, but do you use any other tricks? Or it is just you so dexterous ? 🙂 And what do you think of making tutorial on that, if there’s any trick of course?
Here are all the Eclipse shortcut keys I use. Since you asked I figured I’d deliver. Thank you for the request 🙂