Java: Debug Commons Digester Exception
By admin on Oct 29, 2008 in Java, Programming
This is a exception produced by Commons Digester. After spending few hours to find out the root cause, including studying the source code, I found that I make a silly mistake.
1: java.lang.NullPointerException
2: at org.apache.commons.digester.Digester.createSAXException(Digester.java:3181)
3: at org.apache.commons.digester.Digester.createSAXException(Digester.java:3207)
4: at org.apache.commons.digester.Digester.startElement(Digester.java:1456)
5: at org.apache.xerces.parsers.AbstractSAXParser.startElement(Unknown Source)
6: at org.apache.xerces.parsers.AbstractXMLDocumentParser.emptyElement(Unknown Source)
7: at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanStartElement(Unknown Source)
8: at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown Source)
9: at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
10: at org.apache.xerces.parsers.DTDConfiguration.parse(Unknown Source)
11: at org.apache.xerces.parsers.DTDConfiguration.parse(Unknown Source)
12: at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
13: at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
14: at org.apache.commons.digester.Digester.parse(Digester.java:1827)
One thing to take note is that whenever you have error with any of the commons libraries, do remember to turn on the debugging mode.
1: <logger name="org.apache" additivity="true">
2: <level value="DEBUG"/>
3: </logger>
And it helps a lot for troubleshooting.
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