XPathException

[able lam]

i got the XPathException when passing parameter to Transformer
--- foo.xml ----

<?xml version="1.0"?>
<doc>Hello
        <doc>
                Hello2
        </doc>
</doc>

---- foo.xsl ----

<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
  <xsl param name="param1" select="'default value'"/>
  <xsl:template match="/doc">
        <xsl:apply-templates select="$param1"/>
  </xsl:template>
</xsl:stylesheet>

---- UseStylesheetParam.java ----

.....
..... 
    String paramValue = "doc";
    TransformerFactory tFactory = TransformerFactory.newInstance();
    Transformer transformer = tFactory.newTransformer(new StreamSource("foo.xsl"));
    transformer.setParameter("param1",  paramValue);
    transformer.transform(new StreamSource("foo.xml"), new StreamResult(new OutputStreamWriter(System.out)));
......

I expect "Hello2" will be output, but expection is thrown, how can i solve the problem ??
[ February 13, 2004: Message edited by: able lam ]

[Lasse Koskela]

Could you post the full stack trace of the exception?

[able lam]

i know the problem is the type is not matched,
but i really want to pass '/doc' to $param1

org.apache.xpath.XPathException: Can not convert #STRING to a NodeList!
at org.apache.xpath.objects.XObject.error(XObject.java:740)
at org.apache.xpath.objects.XObject.iter(XObject.java:443)
at org.apache.xpath.Expression.asIterator(Expression.java:288)
at org.apache.xalan.templates.ElemApplyTemplates.transformSelectedNodes(
ElemApplyTemplates.java:245)
at org.apache.xalan.templates.ElemApplyTemplates.execute(ElemApplyTempla
tes.java:215)
at org.apache.xalan.templates.ElemApplyTemplates.transformSelectedNodes(
ElemApplyTemplates.java:429)
at org.apache.xalan.templates.ElemApplyTemplates.execute(ElemApplyTempla
tes.java:215)
at org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(Tr
ansformerImpl.java:2362)
at org.apache.xalan.transformer.TransformerImpl.applyTemplateToNode(Tran
sformerImpl.java:2228)
at org.apache.xalan.transformer.TransformerImpl.transformNode(Transforme
rImpl.java:1306)
at org.apache.xalan.transformer.TransformerImpl.transform(TransformerImp
l.java:704)
at org.apache.xalan.transformer.TransformerImpl.transform(TransformerImp
l.java:1222)
at org.apache.xalan.transformer.TransformerImpl.transform(TransformerImp
l.java:1200)
at UseStylesheetParam.main(UseStylesheetParam.java:95)