[dom4j-user] XSL Saxon, dom4j and NullpointerExceptions

[David Frankson]

I have a large Xerces DOM + Saxon XSL web application that is working smoothly.  I'm considering porting it to dom4j for the cleaner dom and xpath java API.   Several places in a few different xsl documents, I'm getting null pointer exceptions during processing.  I've narrowed it down to the following statement:   <SELECT name="hearingStatus">      <OPTION/>      <xsl:element name="OPTION">           <xsl:attribute name="value">pass</xsl:attribute>           <xsl:if test="$screen[@screeningID=$ID]/hearing/@status='pass'"><xsl:attribute name="selected"/></xsl:if>           pass       </xsl:element> </SELECT>   Its kind-a odd, but I think it has something to do with a xsl:if inside an element when the xsl:if has a "" as part of the test expression.  The $screen/@screeningID attribute does exist as a node, but its value is an empty string.  I have tried it with the full xpath instead of the global variable, and I get the same exception.  I have tried the same xsl:if statement outside the xsl:element and everything works as expected.    Any ideas on where next to look for a solution?  Since this works fine with Saxon and Xerces, I figured it has something to do with dom4j's Document implementation.       Stack trace below:     java.lang.NullPointerException  at com.icl.saxon.expr.NodeSetComparison.evaluateAsBoolean(NodeSetComparison.java:66)  at com.icl.saxon.style.XSLIf.process(XSLIf.java:77)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.XSLElement.process(XSLElement.java:139)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.XSLTemplate.expand(XSLTemplate.java:225)  at com.icl.saxon.style.XSLCallTemplate.process(XSLCallTemplate.java:187)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.LiteralResultElement.process(LiteralResultElement.java:288)  at com.icl.saxon.style.StyleElement.processChildren(StyleElement.java:633)  at com.icl.saxon.style.XSLTemplate.expand(XSLTemplate.java:225)  at com.icl.saxon.style.XSLTemplate.start(XSLTemplate.java:198)  at com.icl.saxon.Controller.applyTemplates(Controller.java:254)  at com.icl.saxon.Controller.defaultAction(Controller.java:270)  at com.icl.saxon.Controller.applyTemplates(Controller.java:235)  at com.icl.saxon.Controller.run(Controller.java:177)  at com.icl.saxon.Controller.transformDocument(Controller.java:1075)  at com.icl.saxon.Controller.transform(Controller.java:945)  at com.infinitecampus.prism.Prism.service(Prism.java:266)