NullPointerException at org.apache.crimson.parser.Parser2.parseInternal

Question

I've tried to use JavaTM API for XML Processing (JAXP), particulary default SAX parser,
which is embeded into JAXP.
I downloaded jaxp-1_1.zip file from http://java.sun.com/xml/download.html, extacted it
and included crimson.jar, jaxp.jar and xalan.jar to java CLASSPATH.
After that I'd tried to parse XML document
with following code
     // prepare SAX parser
SAXParserFactory factory = SAXParserFactory.newInstance();
DefaultHandler handler = new XMLHandler();
try {
// Create a JAXP SAXParser
SAXParser saxParser = factory.newSAXParser();
// url
File file = new File( fileName );
String url = file.toURL().toString();
System.out.println( "URL: " + url );
// parse
saxParser.parse( url, handler );
} catch (Exception ex) {
ex.printStackTrace();
throw ex;
and obtained the message below
java.lang.NullPointerException
     at org.apache.crimson.parser.Parser2.parseInternal(Parser2.java:523)
     at org.apache.crimson.parser.Parser2.parse(Parser2.java:304)
     at org.apache.crimson.parser.XMLReaderImpl.parse(XMLReaderImpl.java:433)
     at javax.xml.parsers.SAXParser.parse(SAXParser.java:346)
     at javax.xml.parsers.SAXParser.parse(SAXParser.java:232)
     at com.darout.bot.parser.PObjectsBuilder.parse(PObjectsBuilder.java:54)
     at TestSAXParser.main(TestSAXParser.java:22)
Could you help me?

Answer 1

I've found an error. It was in my handler implementation.
But is it possible to trace a handler exception correctly?