This happens because the field ( DOMParser parser ) in the class is set to
'null'. The main method does NOT instantiate this field. Instead it
creates a second instance of the parser class whose scope is the main
method only. In order to fix this, you should change the first line in the
main method to 'parser = new DOMParser()' instead of 'DOMParser parser =
new DOMParser()'
Ankit Pasricha
XML Parser Development
IBM Toronto Lab
8200 Warden Avenue, Ontario L6G 1C7
Rob Exley
<[EMAIL PROTECTED]
factory.co.uk> To
[EMAIL PROTECTED]
08/21/2004 04:53 cc
AM
Subject
xml schema validation - null
Please respond to pointer
[EMAIL PROTECTED]
.apache.org
I wouldn't classify myself as a java programmer so be gentle with me....
I am trying to use xerces-j to validate xml documents with an asociated
XML Schema. I have already validated with OxygenXML, xmllint and XSV so
I know all is well. It's just that I would like the option of validating
at run-time also.
I have downloaded some sample code from the IBM tutorial site and
everything seems hunky-dory until I try to enable the schema validation
feature. As soon as the setFeature lines are introduced I start to get
null pointer exceptions being thrown. I would appreciate any help or
guidance that anyone can provide as I am somewhat bemused....
FYI - I am currently trying this against xerces-j 2.6.2 but I seem to
get this error regardless of the version. I have included the source
code as well as the output from running this.
/*
* Created on Aug 16, 2004
*
* TODO To change the template for this generated file go to
* Window - Preferences - Java - Code Style - Code Templates
*/
/**
* @author r_exley
*
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code Style - Code Templates
*/
import org.apache.xerces.parsers.DOMParser;
import org.w3c.dom.Document;
import org.xml.sax.SAXException;
import org.xml.sax.SAXNotRecognizedException;
import org.xml.sax.SAXNotSupportedException;
import java.io.IOException;
public class DOMParserDemo {
private static void setFeature(String
feature, boolean setting){
System.out.println("feature: " + feature);
System.out.println("setting: " + setting);
try {
parser.setFeature(feature, setting);
} catch (SAXNotRecognizedException e) {
System.out.print("Unrecognized feature: ");
System.out.println(feature);
} catch (SAXNotSupportedException e) {
System.out.print("Unrecognized feature: ");
System.out.println(feature);
}
}
public static DOMParser parser = null;
public static void main (String args[]){
DOMParser parser = new DOMParser();
Document doc = null;
setFeature("http://xml.org/sax/features/validation";, true);
setFeature("http://apache.org/xml/features/validation/schema
",true);
// try {
//
//parser.parse("../consumer-score/example_score_request.xml");
// doc = parser.getDocument();
// } catch (IOException ie){
// System.out.println("Could not read file.");
// } catch (SAXException e) {
// System.out.print("Could not create Document: ");
// System.out.println(e.getMessage());
// }
DOMDisplay.display(doc);
}
}
[EMAIL PROTECTED]:~/workspace/schema_validation$ echo $JAVA_HOME
/usr/java/j2sdk1.4.2_04
[EMAIL PROTECTED]:~/workspace/schema_validation$ echo $CLASSPATH
/home/r_exley/build/xerces-2_6_2/build/xercesImpl.jar:/home/r_exley/build/xerces-2_6_2/build/xml-apis.jar:.
[EMAIL PROTECTED]:~/workspace/schema_validation$ java DOMParserDemo
feature: http://xml.org/sax/features/validation
setting: true
Exception in thread "main" java.lang.NullPointerException
at DOMParserDemo.setFeature(DOMParserDemo.java:30)
at DOMParserDemo.main(DOMParserDemo.java:46)
[EMAIL PROTECTED]:~/workspace/schema_validation$
Thanks in advance
--
Rob Exley <[EMAIL PROTECTED]>
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