[xsl] NullPointerException?

[Jay Burgess <jburgess at delanotech dot com>]

After upgrading my version of Xalan yesterday, I've started having null 
pointer exceptions in a Java app doing XSL transformation.  Since I'm still 
somewhat new to XSL, I assume the problem is in my XSL, not with 
Xalan.  First, here's the stack trace:

      [java] javax.xml.transform.TransformerException: 
java.lang.NullPointerException
      [java]     at 
org.apache.xalan.transformer.TransformerImpl.transformNode(TransformerImpl.java:1230)
      [java]     at 
org.apache.xalan.transformer.TransformerImpl.transform(TransformerImpl.java:642)
      [java]     at 
org.apache.xalan.transformer.TransformerImpl.transform(TransformerImpl.java:1092)
      [java]     at 
org.apache.xalan.transformer.TransformerImpl.transform(TransformerImpl.java:1070)
      [java]     at XMLConfig.traverse(XMLConfig.java:172)
      [java]     at XMLConfig.traverse(XMLConfig.java:177)
      [java]     at XMLConfig.traverse(XMLConfig.java:177)
      [java]     at XMLConfig.main(XMLConfig.java:46)

The template is below (it's a simple escape/encode routine for name/value 
pairs in the query string of a URL). From my preliminary debugging, it 
appears that the line "<xsl:with-param name="inString" 
select="string($value1)"/>" is the culprit. It's almost as though value2 is 
trying to set itself before value1 has been fully defined.  Is this 
possible?  If so, do you see any obvious errors in or workarounds for my code?

<xsl:template name="param">
     <xsl:variable name="value1">
         <xsl:call-template name="encode">
             <xsl:with-param name="inString" select="string(.)"/>
             <xsl:with-param name="oldChars" select="'%'"/>
             <xsl:with-param name="newChars" select="'%25'"/>
         </xsl:call-template>
     </xsl:variable>
     <xsl:variable name="value2">
         <xsl:call-template name="encode">
             <xsl:with-param name="inString" select="string($value1)"/>
             <xsl:with-param name="oldChars" select="' '"/>
             <xsl:with-param name="newChars" select="'%20'"/>
         </xsl:call-template>
     </xsl:variable>
     <xsl:text>"&#38;</xsl:text><xsl:value-of 
select="@name"/><xsl:text>="</xsl:text><xsl:value-of select="$value2"/>
</xsl:template>

Thanks in advance.

Jay


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