problem getting a piece of data out of XML

[Sparky]

Greetings -

I have a very simple XML file - just a few lines and each line is a unique piece of data meaning no multiple addresses / names and so on -

I think in XML terms - no children

What I'm trying to do (as a learning deal) is (if I have my vocabulary correct) - parse the file and then pull out some data and print the data.

I assume this is not too complicated.

Before the code I have a Document doc = db.parse(file location)
Nodelist nodelst = doc.getElementByTagName("sample");


Here is the line I think is my working line:

 NodeList sampledata = doc.getElementsByTagName("sample");

                System.out.println("Data = " + sampledata);

When I open the file the data is there but the above code is not displaying the piece of data beside the tag.

Can you show me a little on dealing with a simple XML file?
What simple method can I acquire and display one piece of data within a parsed XML document?

Thanks for the help
Sparky

[eRaaaa]

You are trying to print the NodeList object, that makes no sense!
What do you want is to print the Nodes from the List.

e.g.

		for (int i = 0; i < nodelst.getLength(); i++) {
			System.out.println(nodelst.item(i).getTextContent().trim());
		}

[Sparky]

within my XML file is a few lines
<sample1>
<sample2>

and so on

is there a way w/o a loop to simply "pull" out 1 piece of data?

(More than likely I am misunderstanding how parsing and "getting" items works.)

I thought once I parsed it since I just have 1 piece of data I want I coudl simply get it w/o using a loop.

Thanks
Sparky

[eRaaaa]

If you have only one element with the name "sample", then you will get a NodeList with one Node :) So you don`t need a loop then, you could use System.out.println(nodelst.item(0).getTextContent( ).trim()); e.g.

Or you can use XPath.

It would be helpful if you can give us a full sample xml file and informations about which tag/data do you want so I/we can give you an code example maybe :)

And are you using any external library such as jdom ?

[Sparky]

eRaaaa - thanks for the help

Below is my sample XML file

<root>

  <sample0>A</sample0>
  <sample1>B</sample1>
  <sample2>C</sample2>
  <sample3>1</sample3>
  <sample4>2</sample4>
  <sample5>3</sample5>
  <sample6>4</sample6>

</root>

I would like to just pick out certain pieces - real basic before I go back to the tutorials that have names and address for several people and use the loops and so forth.

I did try JDOM but gave up. I'm using:

import java.net.URL;
import java.net.*;

import java.io.File;
import org.w3c.dom.Document;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Element;

Thanks again -
Sparky

[eRaaaa]

Mhm sorry, I think I can`t help you, I will repeat myself :)
I don`t understand your problem.

If you want to pick out the A of the Tag sample0:

//same
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
		DocumentBuilder db = factory.newDocumentBuilder();
		Document doc = db.parse(new InputSource("YOURFILE.xml"));

//getElementsByTag
		NodeList nodeLst = doc.getElementsByTagName("sample0");
		System.out.println(nodeLst.item(0).getTextContent().trim());

or with childNodes

System.out.println(doc.getFirstChild().getChildNodes().item(1).getTextContent());

or with XPath

//xpath
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;

//......

		XPathFactory xfactory = XPathFactory.newInstance();
		XPath path = xfactory.newXPath();
		XPathExpression exp = path.compile("/root/sample0"); //sample0
		System.out.println(exp.evaluate(doc));

or simple with jdom

	public static void main(String[] args) throws Exception {
		Document doc = new SAXBuilder().build( "YOURFILE.xml" );
		System.out.println(doc.getRootElement().getChildText("sample0"));
	}

all roads lead to Rome :D

[Sparky]

Mhm sorry, I think I can`t help you, I will repeat myself :)

Well you did help!!!

Your code worked with what I wanted - I'm doing something stupid apparently. Inserting your code pulls out the data correctly - of course you knew that.

Can I ask a few questions -

- with NodeList - I should use (indexes) - since it's a list?

(this may explain why all of the examples and tutorials use a loop?)

I think I am confused (or was confused) with NodeList and the use of the index / subscript.

2) If I want to pick out more than 1 piece of data would it be:

NodeList nodeLst = doc.getElementsByTagName("sample0");
NodeList nodeLst2 = doc.getElementsByTagName("sample1");
NodeList nodeLst3 = doc.getElementsByTagName("sample2");

and so on?

Thanks
Sparky

[eRaaaa]

- with NodeList - I should use (indexes) - since it's a list?

(this may explain why all of the examples and tutorials use a loop?)

I think I am confused (or was confused) with NodeList and the use of the index / subscript.

Yes, the API Doc says:
* <p>The items in the <code>NodeList</code> are accessible via an integral
* index, starting from 0.

the reason of the loops are often because there are nodes with child nodes / or a list of nodes :)

2) If I want to pick out more than 1 piece of data would it be:

NodeList nodeLst = doc.getElementsByTagName("sample0");
NodeList nodeLst2 = doc.getElementsByTagName("sample1");
NodeList nodeLst3 = doc.getElementsByTagName("sample2");
and so on?

yes and no :) it will work, but often there are better alternatives - your xml file is a little bit strange in my opinion ^^

[Sparky]

ok

I can easily agree that my XML file is strange - chalk it up to a misunderstanding of the how's and why's of XML

My intent with this XML file was to start there and baby-step into the real uses.

You have been a big help, my questions are answered and I see where I should study and read next - I will keep reading and coding from here!!

Thanks so much!
Sparky